Tuilagi was one of the few players who performed to their best in a disastrous World Cup campaign for England last autumn, but he returned home as one of many players shamed over his disciplinary problems.
The centre was fined on two occasions in New Zealand - firstly for wearing a sponsored gumshield, and then for jumping off a ferry in Auckland.
Tuilagi is yet to play for England since the World Cup, thanks mainly to a shattered eye-socket and a hamstring injury.
He has been restricted to just five games for Leicester this season - the latest of which came in their 20-19 win over Saracens on Sunday.
The 20-year-old was recalled to the England squad last week but faces a fight to dislodge Brad Barritt from the XV after he impressed in England's opening two wins of the Six Nations.
Tuilagi may yet start on Saturday though, as his power could prove vital against a powerful Wales back line, and Lancaster was pleased with his performance in yesterday's narrow win at Vicarage Road.
"Manu has had such limited game time since the World Cup so it was a good chance for him to get another 80 minutes under his belt," Lancaster said.
"At that level, in that quality of a game, it was just a great opportunity for him to play another game. We were pleased for him and how he played. He did a lot of things well. I am pleased with the way that it went."
Tuilagi will begin full training with England on Tuesday after being the day off to recover from yesterday's game, which saw Leicester clinch victory with a last-minute drop goal.
He will have two days to impress Lancaster and prove that he is sharp enough to be considered ahead of Barritt for a game that could make or break England's hopes of winning the tournament, and Lancaster's own chances of landing his current job on a permanent basis.
As well as the return of Tuilagi, Lancaster also has Courtney Lawes and Toby Flood available after they also missed the opening two games of the competition.
England's interim boss would not confirm whether Tuilagi would start, but he did admit having the trio available has breathed new life in to his squad.
He said: "Having that group of players back has given me something to think about.
"From our point of view it's a great position to be in to have competition for places.
"We go in to this match on the back of two wins and we have had a lot of competition in training."
Despite winning their first two games against Scotland and Italy, the Red Rose will have to up their game considerably to top the World Cup finalists in London this weekend.
A lot has been made of Wales' superior brawn in the backs, but Lancaster insists his sole focus remains putting out a team strong enough to deny the visitors what would be only their second win at Twickenham since 1988.
"From my point of view it's about us first. What Wales can bring will be something in the back of mind," Lancaster added.
"It's a big week. We are certainly pleased with how last week went in terms of the quality and the quantity of what we have managed to do in training.
"That sets us up well for a big game."
Third-choice hooker Lee Mears is having a scan on his bicep today and could miss the game on Saturday while wing Charlie Sharples is also a doubt after suffering a leg injury.
Harlequins' Chris Brooker has been called up as cover for Mears.
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