Manchester United take on Bayer Leverkusen in their opening Champions League group stage match on Tuesday evening.
David Moyes goes head-to-head with former Liverpool defender Sami Hyypia, who is starting his second season in charge of the Bundesliga outfit.
Leverkusen currently sit third in their domestic table - just behind Borussia Dortmund and Bayern Munich - after picking up 12 points from their opening five matches, and have the quality to cause an upset at the Theatre of Dreams.
But where will the key battles on the pitch take place - and which Leverkusen players should Moyes' boys pay particularly close attention to?
Stefan Kiessling v Rio Ferdinand & Nemanja Vidic
Make no mistake: Stefan Kiessling is an outstanding striker, capable of inflicting some serious damage on the Red Devils this Tuesday.
The 29-year-old, who was the Bundesliga's top scorer last term after netting 25 goals, could seriously trouble Rio Ferdinand and Nemanja Vidic with his aerial prowess and finishing ability.
Stopping his service into the penalty area will be key - which is where United's full-backs will have a major role to play.
Sidney Sam v Patrice Evra
Germany international Sidney Sam may play on the right wing, but he boasts a decent goalscoring record signing joining Leverkusen in 2010.
The 25-year-old has five goals from five appearances at the start of this season and is likely to pose Patrice Evra one or two problems down that right flank.
Heung-Min Son v Phil Jones/Fabio
South Korea international Heung-Min Son became Leverkusen's record signing in the summer after completing his €10m transfer from Hamburg.
The 21-year-old reportedly turned down a move to Old Trafford in favour of a move to the BayArena - and could inflict further misery on United this week if he can get the better of either Phil Jones or Fabio.
Wayne Rooney v Stefan Reinartz
Stefan Reinartz, the Germany international, is Leverkusen's vital defensive midfielder who will have one heck of a job to keep Wayne Rooney quiet this week.
Rooney scored his first goal of the season against Crystal Palace on Saturday and will have plenty of joy unless Reinartz, 24, is on top of his game.
Marouane Fellaini v Lars Bender
Marouane Fellaini is set to make his first start for Manchester United on Tuesday night.
The powerful Belgium midfielder made an encouraging cameo appearance against 10-man Palace at the weekend, but is likely to have a bit more difficulty against Leverkusen's vice-captain Lars Bender, who boasts plenty of experience.
Winning possession and successfully distributing to the ball will be the order of the day for both tenacious midfielders.
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