EFE AMBROSE will have to re-write the script after Celtic's 2-0 defeat to Kilmarnock yesterday drove a truck through his hope that Celtic would have the SPL title all but tied up by the turn of the year.

Ambrose had hoped to win every game prior to his departure to compete for Nigeria in the Africa Cup of Nations in January.

The centre-half, who has been a huge hit since joining Celtic on transfer deadline day, was banking on his club leaving all other title contenders trailing in their slipstream by then, a notion that now seems fanciful at least following yesterday's surprise setback at Parkhead.

Self-belief, though, is not in short supply and Ambrose is convinced Neil Lennon's side can still put clear daylight between themselves and the rest of the SPL – and get the better of Barcelona in the Champions League return match at Celtic Park.

He said: "That would make it a bit easier for me to go and join my nation. I will be away for about three weeks if we reach the final, and I believe we will do that."

Nigeria are in Group C of the continental competition along with Zambia, Burkina Faso and Ethiopa and Ambrose is no stranger to mixing it with the best the game has to offer. He and goalkeeper Fraser Forster both earned a place in Uefa's team of the week in recognition for their efforts in the Camp Nou in midweek, but this was actually Ambrose's third run-in with the Argentinian superstar.

Ambrose had watched on from the bench as Messi and co won the Olympic final in Beijing in 2008 and the teams had met in a friendly in South America in September 2011. "It was amazing to be in the team of the week as I never expected it," Ambrose said. "It brought me great joy, but I believe the 11 Celtic players from Tuesday deserved to be in that team. We are all players of the week."

Playing in the Champions League has its own difficulties, namely the increasing likelihood of other clubs swooping for key men such as Ambrose, Victor Wanyama, Gary Hooper, Fraser Forster and perhaps even Lennon himself. If reports linking him with the technical director's role at Tottenham Hotspur and West Bromwich Albion are to be believed, you can throw in director of football development John Park as well.

"John's done a brilliant job for us," said Lennon. "We have very similar ideas on the game and the players he brings to our attention, some work and some don't but overall he's done really well. He'd be a loss if he was to go. He's an important piece of the jigsaw here."

If the late nature of defeat in the Camp Nou on Tuesday night allows Celtic to harbour thoughts of revenge, the same is true of St Johnstone, who they meet on Scottish Communities League Cup duty in midweek. The Perth side are the only other team to have beaten Celtic this season, by an identical come-from-behind scoreline at McDiarmid Park, and there is little prospect of Lennon letting up in the only domestic competition to so far elude him as a manager.

"We have been to two finals and I would like to get back there and go one better," said Lennon. "St Johnstone are, along with ourselves, probably the form team in Scotland at the minute. They are the only team to beat us domestically and we will need a better performance than we turned in at McDiarmid Park."

The Perth side have been doing so well, in fact, that Lennon's countryman Steve Lomas has relieved the early season pressure and now finds himself linked with the Burnley job. "I am not surprised," Lennon said. "Steve knows what he wants to do in the game so it is great exposure for him. He was under a bit of pressure – I remember speaking to him at the start of the season and he felt, looking at the games, they wouldn't get off to a good start, but they got a great lift from beating us and have not looked back."