THE opportunity has been earned, and now is the time to finish the job.

Celtic's Champions League future may have become shrouded in doubt by defeat in Lisbon this week but Efe Ambrose is refusing to take Benfica's revival as a reason to doubt his side's chances of reaching the last 16 of the competition.

The ebullient Nigerian defender accepts that Neil Lennon's team no longer have complete control of their destiny – even a victory against Spartak Moscow would be insufficient should Benfica win in Barcelona – but insists that victory over the Catalan club at Parkhead is evidence of Celtic's capabilities.

"In that match, we made things difficult for [Lionel] Messi and he will never forget playing against a team like Celtic," the centre-back said. "That is the spirit we will be taking to the last game to make sure that we win, though the result from the other game will determine our fate. But we are going to do our best to ensure that we make it through.

"I strongly believe that we are going to make it, we started well and we want to finish the good work. I know that it is going to be tough but we are ready to face the challenges of qualifying from the group. Our last game is in Scotland and we will be back on our ground and we need to win the last game against Spartak Moscow.

"It was a great achievement to beat Barcelona and I can never forget that game. But in the whole of the Champions League, we are looking beyond just beating Barcelona; we want to go far in the competition."

Celtic's performances so far have been burnished by the efforts of Fraser Forster, who has made more saves than any other goalkeeper in the competition this season. The Englishman has recorded 49 saves in just five games for Lennon's side, who have held the ball for just 38% of their games and have a pass completion rate of just 55%. Only Romanians CFR Cluj fare worse in those two categories. The Scottish champions do fare better in one category, though: captain Scott Brown is second behind Bate Borisov's Vitali Rodionov for fouls committed.

None of that has put off Celtic trialist Juan Agudelo, though, with the USA striker insisting he covets a move to Europe. The Chivas USA player has spent his close season at Lennoxtown and has enjoyed the experience. "I know the history," Agudelo said. "It's basically a religion for many. Just to have that there and have the support of the city would be lovely. I'd have to consider a lot of things but definitely, Celtic is a great club."