Ambrose was fined for a breach of club discipline after failing to show up on time ahead of Celtic's final training session on the morning of their match against Juventus. The 24-year-old had to take a taxi to get to the session and was then disciplined by Lennon. He was a substitute in the 2-0 defeat which sent Celtic out of the Champions League last 16 on an aggregate of 5-0, although Lennon said that had been the plan even before he had missed the bus.
Both legs of the Juventus tie were regrettable for the Nigerian internationalist. After rushing back from the Africa Cup of Nations final in time for the first leg, he was at fault in two of Juventus's three goals at Parkhead and had his performance publicly criticised by team-mate Kris Commons. Having missed a fine chance to score with a header in Glasgow he was similarly at fault by squandering an opportunity with another poor header in Turin.
"If Ambrose could head it then both ties would have been different," said Lennon. "I mean, he's missed another one from four yards out."
Earlier in the group stage he almost missed the team flight to Barcelona after forgetting his passport. "He's just let himself down," said Lennon of the incident in Italy. "He was 10 minutes late and we left without him because he's only got to get out of his bed, walk down and get on the bus. Anyway, he's been disciplined for it. Whether he would have started the game or not has nothing to do with what happened; we were of a mind to go with Victor [Wanyama] and Kelvin [Wilson] at the back anyway, just to give us that stability. I thought they were excellent."
Asked if he felt Ambrose owed him an apology, Lennon said: "He owes me a fine as well. He's going to be a few quid out of pocket by the end of the week."
Ambrose has had a generally impressive debut season and made 31 appearances since joining Celtic from the Israeli club FC Ashdod last summer, although his poorer performances against Juventus came after being away at Nigeria's Africa Cup of Nations victory in South Africa. Lennon said it would be misleading to suggest Ambrose had been tired since that tournament. "No, he's a fit boy. I think he played [only] three or four games in Africa because he was suspended. He's played more or less the same amount of games as everybody else so you can't use that as an excuse. After the Juventus first leg he came back and scored two goals in two games for us. He has just tailed off a wee bit so maybe there's a little bit of mental fatigue rather than physical fatigue. But there's no serious issue there."
Both Wanyama and Adam Matthews are expected to miss tomorrow's game at Ross County, and possibly other fixtures after that, having suffered hamstring strains which led to them being substituted against Juventus.