David Moyes, Man U's new head coach. (Flickr)

This group features two national champions from England and the Ukraine, a German squad that has been known to upset odds-on favorites and a Spanish surprise qualifier. As all four sides have been undergoing significant transitions, this group presents the first major international challenge for the freshly curbed teams of Manchester United, Shakhtar Donetsk, Bayer Leverkusen and Real Sociedad. Here's an assessment of their chances in the 2013-14 Champions League:

Manchester United

Qualified as: National Champions in English Premier League

Key additions: new head coach David Moyes (Everton), midfielder Marouane Fellaini (Everton)

Key losses: head coach Sir Alex Ferguson (retired), midfielder Paul Scholes (retired, now assistant coach)

Biggest achievements in Europe: 3x Champions League winners ('68, '99, '08)

Coming off their record-setting 20th Premier League title, Man U is facing some major changes. Sir Alex Ferguson, who has left one of the most remarkable imprints on a team in European soccer history,  retired at the end of last season after 17 years with the club. While the team was dominating the national competition, finishing 11 points ahead of local rivals Manchester City, Ferguson was not able to lead his team past Real Madrid in the Champions League's round of 16. Following surprising struggles against Galatasaray and Cluj, in what was expected to be an easy group for the Red Devils, Man U earned a hard-fought draw in Madrid, but fell to the Spanish side in the second leg at home. 

As Ferguson's replacement, the team hired former Everton coach David Moyes. While having been successful and popular in Everton, he is now facing two interrelated immense challenges. First, he will have to capture the heart of a club that many assume will be overshadowed by the great 'Sir Alex' for a long time to come. Secondly, he will have to find a way to deal with club icon Wayne Rooney. The English national striker has repeatedly voiced interest in leaving the club, potentially for Chelsea, but his request has been delayed by the club for another season. Meanwhile the club has been eyeing Aston Villa power striker Christian Benteke as a potential replacement and added some depth at midfield with former Everton midfielder, Marouane Felliani. The 25-year old Belgian enjoyed playing under Moyes and will increase ManU's creative variety. 

Starting into the new season, ManU has only gone 1-1-1, falling to archrival Liverpool and failing to beat Chelsea at home. David Moyes will need to gain some respect quickly in order to keep things calm around the team and Wayne Rooney. Victories in the first two games against the two hardest opponents ingroup A, Leverkusen and Donetsk, would earn Moyes something to show for, while anything else will be perceived as sheer disappointment.

Prediction: While the start in the new season and Man U's last appearances on the European stage have shown that the team is still finding a way back to the glory ways of the old days, the club remains a European powerhouse. With the re-signing of Portuguese winger Nani, English top scorers Robin Van Persie and Danny Welbeck, defenders Evra and Vdidic, as well as Japanese wingers Shinji Kagawa and Ashley Young, Moyes still has a multitude of dangerous weapons at his disposal. If he finds a way to use them efficiently, Man U will win this group and will advance as far as the quarter finals.

Bayer Leverkusen

Qualified as: 3rd in German Bundesliga

Key additions: striker Heung-Min Son (Hamburg), midfielder Emre Can (Bayern Munich)

Key losses: striker/winger André Schürrle (Chelsea), defender Daniel Carvajal (Real Madrid)

Biggest achievements in Europe: Six appearances in Champions League, runners-up in 2002; won UEFA-Cup in 1988

Bayer Leverkusen have shown that they have great potential and can upset European heavy weights. In their last Champions League campaign in 2011-12, the 'Werkself' went 3-0-3, stealing a game from Chelsea and Valencia respectively. They were then eliminated however, not standing a chance against Barcelona. Last season, they were the only team in the German Bundesliga to beat the reigning Champions of Germany and Europe, Bayern Munich. They finished third overall in the national competition, just one point shy of Champions League runners-up Borussia Dortmund. 

Meanwhile, Leverkusen's last season in the Europa League tells the other side of the story. After advancing from a manageable group stage, the Germans conceded a disappointing end to their European campaign against Benfica Lisbon. While impressing on the national level, Leverkusen is lacking consistency on the international stage. Their quick, flexible attacking game will suffer in diversity from the loss of German international striker André Schürrle, who has emerged as one of the nation's most promising, creative talents. The addition of additional firepower through Korean striker Heung-Min Son will only fill this void to a certain extent. Stefan Kießling, Germany's top scorer with 25 goals last season, and Sidney Sam will now rely more heavily on the young, up-in-coming midfield axis formed by Lars Bender, Stefan Reinartz and Simon Rolfes. They will be joined by another talent, Emre Can, but will have a hard time exonerating the team's defense from offensive pressure of Eruopean class. The young, versatile team consists of several components who have experienced international competition already, but the departure of Daniel Carvajal will leave the defense more vulnerable. 

Leverkusen has started strong in the national competition this season with three consecutive victories, but lost a tough game in Schalke.  The team is talented and young and bound for a great season and future in the Bundesliga, but Leverkusen still needs to grow, in order to become a great European force to be reckoned with.

Prediction: Don't be surprised if Leverkusen manage to steal one from Man U! In the 2002-03 group stage, they proved to be a hard nut to crack for the Red Devils, who beat them in two exciting games (0-2, 1-2). The year before, setting the stage for Leverkusen's only Champions League final performance, Leverkusen even eliminated Sir Alex Ferguson's team on away goals on an aggregate 3-3 score. Leverkusen has the potential to finish second in this group, but due to their recent costly losses of Schürrle and Carvajal, they will probably not be able to be more consistent and will not go much further than the round of 16. 

Stefan Kiessling led his German squad with 25 goals last season. (Wikimedia Commons)

Qualified as: Ukrainian national champions

Key additions: attacking midfielder Frederico Rodrigues Santos (S.C. Internacional), winger Bernard (Atlético Mineiro)

Key losses: attacking midfielder Henrikh Mkhitaryan (Borussia Dortmund), Fernandinho (Manchester City)

Biggest achievement in Europe: quarter finals in Champions League 2010-11; UEFA-Cup winners 2009

The Ukrainians have dominated the Ukrainian league, wining consecutive titles over the last four seasons. This year however, they seem to have found a worthy contender in Metalist Kharkiv, whom they are trailing by one point in the current competition. In Europe, Donetsk has gained respect through their strong Champions League campaign in 2010-11 and last year's second place in the group stage in which they managed to tie at Juventus and beat and eliminate the English powerhouse Chelsea. Yet, in the round of 16, Borussia Dortmund proved to be too strong. 

Donetsk's roster, including Croatian right back Darijo Srna, Brazilians Luiz Adriano and Maicon, as well as Croatian striker Eduardo has been complemented by two additional Brazilian forces, Adriano Mineiro and Frederico Rodrigues Santos. Losing super-talent Mkhitaryan will constitute a heavy burden on Donetsk. The Armenian international scored 25 goals in 29 games for Shakthar and was voted Commonwealth of Independent States player of the year in 2013. While Adriano has already contributed five goals this season in Ukrainian Premier League, the team's most recent and most prominent two additions will need to compensate for the loss in intelligence and flexibility that 'Micki's' departure has caused. 

Prediction: Donetsk will once again be contenders for the second seed in the group, but due to Mkhitaryan's transfer to Dortmund, they will fall short.  

Real Sociedad

Qualified as: 4th seed in La Liga; beat Olympique Lyon in qualifiers

Key addition: striker Haris Seferovic (Florence)

Key loss: midfielder Asier Illarramendi (Real Madrid)

Biggest achievements in Europe: Champions League group of 16 in 2003-04

The Spanish surprise of last season enters this year's Champions League competition as an underdog. However, their two 2-0 victories over strongly favored Olympique Lyon in the qualifying round play offs, should serve as a warning signal for their group A opponents. Other spanish outsiders such as Atlético Madrid, Malaga and Atlético Bilbao have profited from being underrated in recent years as well.

The addition of Swiss striker Haris Seferovic seems to be paying off. He netted a goal right in his first international appearance thus initiating the team's successful run for Champions League qualification. Another notable player in their roster is local shooting star defender Iñigo Martínez, as well as Mexican striker Carlos Vela. Vela has scored 16 goals in 39 appearances for the Basques. 

However, Asier Illarramendi's decision to leave the club for Real Madrid has yet to be compensated. His quick, impulsive genius moments will certainly be missed.

Prediction: Real Sociedad is back after an eight year absence for what will be their fifth overall Champions League campaign. The little known underdog has potential and a young, hungry squad which could create one or two upsets. They have struggled however, only winning one of three games this season in La Liga, and their lack of international experience and the loss of Illarramendi will be too much to overcome, which is why they will not advance to the next round.

Reach Staff Writer Alex Wowra here. Follow him here.