Celtic begin their Champions League Group G campaign tonight with a match against Benfica at Parkhead.
Here's a look at the key battles.
CHARLIE MULGREW v OSCAR CARDOZA
Mulgrew has been one of the most reliable defenders at Celtic Park in recent years and offers a threat going forward and from set-pieces. However, he has been nursing an Achilles problem in recent weeks which is not ideal when you are up against one of the most potent strikers in Portuguese football. Cardoza, 29, who was linked with a £20million move to Chelsea this summer, scored in a 1-0 win against Celtic in Lisbon when the two teams met in the 2007/08 Champions League and will again pose a threat.
SCOTT BROWN v PABLO AIMAR
Brown is another Celtic player who has been playing through the pain barrier. An ongoing hip problem needs to be managed, but Celtic boss Neil Lennon is a huge admirer of the Scotland midfielder's drive and energy and will ask him to help win the midfield battle against the talented Portuguese side, which will not be easy. The skill and experience of Aimar, the veteran Argentina international, is sure to provide the home side with a stern test.
GARY HOOPER v EZEQUIEL GARAY
Hooper has yet not reached top form this season but scored one of the goals to help Celtic beat Helsingborg in the Champions League play-offs. The former Scunthorpe striker comes alive in the box and will have to be at his best if he is to get any joy from 25-year-old Argentina international Garay, the bedrock of the Benfica defence, who signed from Real Madrid last year and who has posted a warning to the Parkhead side by saying: "Do we want one point in Glasgow? No."