The Spaniards are 4-11 with Hills to come back from 2-1 down and put the Gunners out. William Hill now make Arsenal 16-1 to win the Champions League with Barca still favourites at 7-4.
Outrights (William Hill): 5-1 Real Madrid, Chelsea; 6-1 Man U, 16-1 Arsenal, Spurs, 20-1 Bayern Munich, Inter Milan, 33-1 AC Milan, 40-1 Shakhtar, 50-1 Schalke, 66-1 Roma, Valencia, 125-1 Lyon; Marseille, 250-1 Copenhagen.
Cesc Fabregas is out from 6-4 to 7-4 with William Hill to join Barcelona by the first day of next season and 2-5 not to.
An Arsenal v Spurs final is 40-1 with Hills who make Chelsea 11-8 ahead of 2-1 Man United, 4-1 Spurs and 9-2 Arsenal to be the English side that goes furthest.
Lionel Messi again failed to score on English soil on Wednesday night and bet365 have cut their price on him firing a blank in the last 16 from 10-3 into 6-5.
Liverpool are 1-4 with William Hill to reach the last 16 of the Europa after drawing 0-0 away to Sparta Prague.
Rangers are out to 11-4 after conceding a last-minute equaliser to Sporting Lisbon at Ibrox.
Outrights (William Hill): 4-1 Man City, 6-1 Liverpool, 13-2 Porto, 8-1 Zenit, 14-1 CSKA Moscow, Villarreal. Others on request.