Previous European Cup/CL best: Winners: 1987, 2004
Manager - Julen Lopetegui: A former goalkeeper, Lopetegui was on the books of both Real Madrid and Barcelona during his playing career, although he rarely featured for either of the La Liga giants. Since his retirement, the 48-year-old has mainly been working the Spanish national side at youth level, before being appointed by Porto in the summer. Since then, he has added seven of his fellow Spaniards to the squad, including Cristian Tello and Oliver Torres.
Key Player - Jackson Martinez
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The Colombian may not have been first choice for his country during the summer's World Cup, but he has returned to his club duties in clinical fashion. Heading into the Champions League group stages, he has scored five league goals for Porto, as well as one in the qualifying round against Lille. On top form, the 27-year-old has the pace and power to cause problems for any defensive unit in the competition.
Sports Mole says: The Portuguese outfit have found themselves drawn in a group that contains two teams that possess similar qualities to themselves. Lopetegui has added a youthful Spanish flavouring to his squad, which is likely to make them a vibrant and exciting side to watch. It will be tight, but Porto should squeeze themselves into the knockout stages.
Did you know?: Porto have appeared in the final of Europe's top club competition twice and won on both occasions.
Previous European Cup/CL best: Quarter-finals: 1957
Manager - Ernesto Valverde: Now in his second spell in charge of Athletic, Valverde is a popular figure in the Basque region. His sides are always well organised, but that does not come at the expense of creativity. While the two Madrid clubs and Barcelona battled it out for the title, Bilbao, under Valverde's watch, held off a spirited fight from Sevilla to finish fourth and make the qualifying rounds of this season's Champions League, where they would impressively see off Napoli.
Key Player - Ander Iturraspe
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Often sitting at the base of the Athletic midfield, it is Iturraspe's responsibility to dictate the tempo. The 25-year-old is not the type of midfielder that is going to score many goals or dribble beyond two or three opposition players, but he rarely gives away possession and is fully aware of his limits. Such qualities have not gone unnoticed by Spain head coach Vicente del Bosque, who handed Iturraspe his international debut earlier this year.
Sports Mole says: No side will relish a trip to the atmospheric San Mames and Bilbao will need to make the most of that. Of their 19 home La Liga matches last term, Bilbao won 13 and lost just twice. If they can take that form into the group stages, qualification should be secured.
Did you know?: No player has made more appearances for Athletic in UEFA competition encounters than defender Andoni Iraola, who has featured in 41 matches.
Previous European Cup/CL best: Quarter-final: 2011
Manager - Mircea Lucescu: At the age of 69 and having coached the likes of Inter Milan, Galatasaray and the Romanian national side prior to him filling the Shakhtar hotseat a decade ago, Lucescu will be the most experienced manager in this season's Champions League. The Miners have won eight Ukrainian league titles under his guidance, as well as having reached the last eight of the Champions League in 2011, when they were knocked out by Barcelona.
Key Player - Luiz Adriano
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There are 13 Brazilians within Shakthar's senior squad, but few are more effective and important than Adriano. A pacey striker with a keen eye for goal, the 27-year-old found the net on 25 occasions in all competitions last term, including three in European fixtures. If Shakthar are to stand any chance of reaching the first knockout round, Adriano will need to be clinical when chances come his way.
Sports Mole says: It really is a close run thing between three of the teams in this group, one of which is Shakhtar. They will be stinging from missing out on qualification last term when they finished behind Manchester United and Bayer Leverkusen. Getting off to a good start would do their chances of advancing the power of good, but it would not be a surprise to see them fall short.
Did you know?: Shakhtar have won six of their most recent opening seven group matches in all European competitions.
Previous European Cup/CL best: Group stages: 2008, 2011, 2013
Manager - Alyaksandr Yermakovich: Having spent the majority of his playing career with BATE and then undergoing a five-year stint at the Borisov Arena as an assistant coach, it seemed logical that Yermakovich would be the choice to fill the hotseat when it became vacant in the summer of 2013 following the departure of Viktor Goncharenko. This campaign will be the 39-year-old's first as a manager in the Champions League, although he did play in the competition with BATE.
Key Player - Mikhail Gordeichuk
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The 24-year-old midfielder only arrived at BATE from Belshina Bobruisk earlier this year, but he made a positive impact during his debut season. From midfield, Gordeichuk contributed eight goals, including braces in victories over Torpedo Zhodino and his former employers. He also has experience of having represented Belarus at the Olympic Games in London two years ago.
Sports Mole says: The group's minnows have pulled off shocks before, none more so than their defeat of eventual champions Bayern Munich two seasons ago. Even so, it looks a tall ask for the club from Belarus to reach the knockout stages. Qualifying for the Europa League is not out of the question, though, with a lot depending on the results that they collect in front of their own supporters.
Did you know?: BATE have never lost a opening group game in the Champions League.
Group H fixtures
Wednesday, September 17
Porto vs. BATE
Bilbao vs. Shakhtar
Tuesday, September 30
Shakhtar vs. Porto
BATE vs. Bilbao
Tuesday, October 21
BATE vs. Shakhtar
Porto vs. Bilbao
Wednesday, November 5
Shakhtar vs. BATE
Bilbao vs. Porto
Tuesday, November 25
BATE vs. Porto
Shakhtar vs. Bilbao
Wednesday, December 10
Porto vs. Shakhtar
Bilbao vs. BATE
Prediction: 1. Bilbao 2. Porto 3. Shakhtar 4. BATE