Man Utd 0-0 Villarreal: The hosts' Carlos Tevez looks to get the better of Edmilson in his search for an early goal at Old Trafford

They have an appeal for a penalty turned down when Park Ji-Sung appears to be tripped by Joan Capdevila in the Villarreal box

A dangerous ball heads into Villarreal's area but goalkeeper Diego Lopez cuts it out as they continue to frustrate the Red Devils

Guille Franco hits the post for the Spaniards before Sir Alex Ferguson introduces a lively looking Cristiano Ronaldo with 25 minutes to go

The Portuguese winger picks out Jonny Evans at the death but he heads against the post as Man Utd have to settle for a draw

Dynamo Kiev 1-1 Arsenal: After scoring a hat-trick at Blackburn on Saturday, Emmanuel Adebayor attempts to add to his tally in Ukraine

Fellow striker Robin van Persie goes close on a couple of occasions as the Gunners begin to create chances

At the other end Ismael Bangoura takes a tumble under pressure from Arsenal captain William Gallas as Dynamo try to break the deadlock

Bangoura does eventually open the scoring with a 64th-minute penalty to leave Arsene Wenger's side in a precarious position

Defeat looks likely for the Londoners until Gallas pokes home from Theo Walcott's cross two minutes from time

Celtic 0-0 AaB Aalborg: Marek Saganowski tries to fashion an opening for the visitors as the sides begin their Group E campaigns

The Danish side win an early free-kick but Michael Jakobsen curls his effort wide of Artur Boruc's goal

Celtic have a superb chance to take the lead on the half hour when Shaun Maloney wins a penalty but Barry Robson misses the spot-kick

With 15 minutes remaining Georgios Samaras is presented with a great chance to score but he takes too long to get his shot off

Aalborg have Michael Beauchamp sent off in the closing stages but they hold on to claim a point against the Scottish champions