Leo Cullen hailed the return of Caelan Doris after the Ireland back row played the full 80 for Leinster against Ulster on Friday night.
Doris, 23, was stood down from playing just before the Six Nations championship got underway due to 'concussive symptoms', with Leinster and Ireland deciding the best course of action was a period away from competitive action.
The Mayo man, who at that stage looked on course for a first Lions tour this summer, was due to return in the Rainbow Cup opener against Munster last month.
Had he played then, Doris might have had involvement in the Champions Cup semi-final the following week in La Rochelle but a calf issue kept him out against Munster.
However he did start and finish against Ulster and had some good moments in the 21-17 victory at the RDS that keeps the Blues' slender hopes of reaching the June final alive.
"Yeah, that's one of the real positives from the game I think, getting Caelan back and through 80 minutes," said head coach Cullen.
"We were wondering whether we would keep him on and let him run the 80, we were contemplating taking him off a little bit earlier, but I thought he looked strong in the game.
"He maybe looked a little bit tired towards the end, naturally, but it was a great shift for Caelan to get through.
"He was a little bit unlucky, had a bit of a false start here a couple of weeks ago leading into that Munster game. But he's going to be a hugely important player for the club, hopefully long into the future.
"He's still very young and building experience all the time, but it's been a big year, and I suppose a big couple of seasons for Caelan.
"He was unlucky the way it played out for him leading into the Six Nations, but it's great to have him back out there."
Asked how Doris has dealt with missing out on a second Six Nations and big games for Leinster, Cullen replied: "I think there is always a bit of a natural frustration but he's trained well with the group going through his return to contact.
"You can see him out there, he was into everything, so he's certainly not holding back.
"He would have got confidence from the 80 minutes and getting through the game, so we'll see how he is next week.
"Obviously we have no game for the next couple of weekends but we'll have a nice competitive group for Glasgow and for Dragons in the last two rounds."
