Champion Barcelona will bid to get its Champions League title defence back on track on Wednesday as Arsenal and AC Milan also look to keep the dream alive in the second round of elite European matches.
But English giant Chelsea, which has already got its campaign off to a winning start, is set for possibly its toughest group assignment when it meets Spanish side Valencia at the Mestalla.
Barcelona was held 2-2 by AC Milan at the Nou Camp in its Group H opener, but despite riding high after a 5-0 hammering of Atletico Madrid in La Liga, coach Pep Guardiola warned against complacency as the Catalans travel to Minsk to face Belarusian champion FC Bate Borisov.
Both sides are level in Group H on one point after Bate drew 1-1 at Czech champion FC Viktoria Plzen.
Mata's return
Chelsea boss Andre Villas-Boas' side will be looking to take a big step towards the last-16 when it travels to Spain with striker Juan Mata, just one month after he left Valencia for Stamford Bridge.
Chelsea sits top of Group E after a 2-0 home win against Bayer Leverkusen
Fellow Londoner Arsenal is second behind French club Marseille in Group F after a late goal gave German champion Borussia Dormund a share of the points. Arsene Wenger is keen for maximum points from the three home fixtures against Olympiakos, Dortmund and Marseille to help them reach the 11-point target he has set to ensure qualification to the knock-out stages.
The Gunners has a major doubt over winger Theo Walcott (knee injury) as it hosts Greek club Olympiakos. Marseille hosts Borussia Dortmund in the second Group F tie.
In Group G, Europa League champion FC Porto travels to Zenit St. Petersburg.
