Some personal ambitions for the second leg have been hardened, and a point of principle has still to be contested, but otherwise Neil Lennon has purged the Juventus game from Celtic's system.

The manager cannot allow a subdued mood to settle on his squad, not least because there is a championship and a Scottish Cup to pursue. Even so, the swiftness of the way the team restored its purpose was enough to overwhelm Dundee United.

The 6-2 victory last weekend was an act of renewal. Lennon has set his team the target of winning the second leg in Turin to restore the pride of a significant campaign, and he continues to seek clarification from UEFA on the shirt tugging and man-handling that the Juve defenders were allowed to employ while marking Celtic's attackers. Causes provide a source of motivation, yet Lennon himself acknowledged before the United game that the coaching staff sometimes need to be picked up after a result as disappointing as the 3-0 loss to Juventus.

That rejuvenation must come from within, though, since it was Lennon who had to address his squad and remind them of their status and achievements. "Look lads," he told them, "you're in the last 16 of the Champions League, you've done all right. You're a good side and were just beaten by a very good side. There is no shame in that."

The visit to St Johnstone tonight would appear to be routine in the context of the team's European achievements, but there is a resolve among the players to secure the Clydesdale Bank Premier League title as soon as possible.

It was understandable that Lennon dwelled upon the contributions of his two centre-backs, though. In differing ways, Kelvin Wilson and Efe Ambrose are resurgent figures who could be considered emblems of the team's development. The latter had allowed his foibles to be exposed and exploited by the Italian champions to such an extent that his team-mate, Kris Commons, was critical in the immediate aftermath of the game.

Ambrose was cheered by the Celtic support against United, then scored the equalising goal only moments after the visitors had taken the lead. The header was powerful and accurate, the two qualities so glaringly absent from the header he misjudged when unmarked in the Juventus penalty area.

"It was more or less the same kind of position," said the manager ruefully. According to Lennon, the Nigerian centre-back has begun to attract the attention of clubs across Europe, but the development that has still to come, and the positive effect of his partnership with Wilson, are reasons enough for Celtic to discourage any interest.

"It was a great reaction from [Efe Ambrose]," Lennon said. "He's pretty strong-minded. He's not aloof, he's very humble and was very disappointed after Tuesday night. Overall he's been brilliant for us. I don't think we'll lose him in the summer as he's just in the door and there's more he can add to his game. But he has got a few admirers out there. He's brought the best out of Kelvin Wilson as well. At European level, they've made us better."

Both centre-backs have flaws that are still to be eradicated, and while the Celtic players were celebrating Ambrose's equaliser last Saturday, Lennon called Wilson over to the touchline to discuss the positioning errors that led to United's opening goal. The Englishman was uncertain and at times unsteady in his first season, but his display against Juventus was refined enough to impress the watching England manager, Roy Hodgson.

There is a hierarchy of candidates above Wilson for the England squad, and Lennon used Hodgson's remarks as a way to praise his player rather than push hard for his inclusion. It is a measure of the improvements in Wilson's game, though, that he is a regular in Celtic's starting line-up and increasingly considered a vital part of the side.

"Roy Hodgson was very complimentary about him," Lennon said. "He did himself no harm at all. With England I certainly think he's worth looking at. He's a modern day centre-half who is composed on the ball. He's improved aspects of his game like his heading. He also has pace, which is a huge asset at any level. Kelvin had a few things in his private life which unsettled him when he first came here. I also don't think he realised how big the club was and the pressure which came with it. But this season he's been magnificent and very consistent."

When Wilson left Nottingham Forest and moved to Glasgow, it was the first time in his life that he had lived outside the Midlands. The unsettling nature of the move in the summer of 2011 was exacerbated by the recent birth of his young daughter, and for a time the issues in his private life seeped into his game. Wilson is more focused now, and the reward has been regular appearances and plaudits. Consistency has been evident, although the defender is reserved about the talk of an England call-up.

"It's nice to be spoken about it in those terms, but I've not really thought about England," he said. "I was involved with the Under-20s once or twice and played a game in Moscow. If it comes along it would be a great achievement. If you look at the teams I've played against, then it's been a good spell for me."