Celtic play host to Barcelona in the Champions League on Tuesday night, hoping for a repeat of last year's famous win at Parkhead.
Here, Press Association Sport looks at the key battles.
EFE AMBROSE v NEYMAR
Nigerian defender Ambrose featured in both meetings with Barca last season and particularly impressed in Celtic's 2-1 win at Parkhead. He may have breathed a sigh of relief when Lionel Messi was ruled out this time with a thigh problem but his absence could pave the way for Neymar to shine following his £50million capture in the summer. Two-footed and an impressive finisher, the Brazilian will be a threat.
SCOTT BROWN v XAVI
Hoops skipper Brown tends to rise to the big occasions and has plenty of experience in the Celtic engine room on European nights such as this one. He will be called upon to lead by example but is set to come up against another player with bags of experience. Xavi came off the bench to replace the injured Messi at the weekend to make his 450th league outing for the Catalan giants, again highlighting his status as the club's record appearance holder.
GEORGIOS SAMARAS v GERARD PIQUE
Samaras has been on fine form for Celtic in front of goal in recent European campaigns, including a goal against Barcelona last term. He enjoyed the best possible preparation for this match with a hat-trick against Kilmarnock on Saturday. The visitors head into the tie with a defence weakened by the absence of Javier Mascherano, Jordi Alba and Carles Puyol but have still enjoyed their best start to a league season in the club's history. Key to that statistic has been Pique, who has been solid in defence and who has started all 10 competitive matches so far this term.