Rory Best believes Ireland team-mate Johnny Sexton is back to his "nightmare" best - just in time for the summer's British and Irish Lions tour to New Zealand.
Skipper Best hailed out-half Sexton as the Irish crushed England's back-to-back Grand Slam dreams with a 13-9 triumph in Dublin.
Sexton has ground through a persistent injury glut in the last 12 months, but ended the RBS 6 Nations with a return to top form which could yet be enough to secure him the Lions' starting fly-half berth once again.
And Best admitted New Zealand would not enjoy facing Sexton in the summer's three-Test series if the 31-year-old gets the Lions nod.
"The guy's a competitor. Probably the best thing you can say is that I definitely prefer playing with him in the green of Ireland than playing against him when he's with Leinster," said Best.
"He's a bit of a nightmare to play against and he just has this real will to win.
"There's a few out-halves in world rugby now that have it, especially in the northern hemisphere.
"He's a real warrior on the pitch but a really humble, good guy off it"
"But as much as anything what we see on the pitch, that competitor that he is, that's what you need to win games and that's all that is.
"Johnny off the pitch is a really, really good guy.
"The way Paddy Jackson learns off him and the way the team feeds off him, it's great.
"He's a real warrior on the pitch but a really humble, good guy off it."
Sexton and England playmaker Owen Farrell share the same dogged, aggressive approach, and even clashed several times as the visitors failed to register an outright world-record 19th consecutive victory.
Lions coach Gatland could well pair Sexton at fly-half and Farrell at 12 in a bid to capitalise on the obduracy and accuracy of both men at the same time.
While Best was left frustrated with referee Jerome Garces refusing to scrutinise a number of borderline late hits on Sexton from England, the Ulster hooker insisted Eddie Jones' men had not crossed any lines with their conduct.
Best told Garces "it's my responsibility to protect my players", but received no change from the official, although he later remained relaxed about the affair.
"It was frustrating and he (Garces) kept saying he and the other officials were keeping an eye on it," said Best.
"And all I said was that it's my job as captain to look after my players. I told him to make sure our players were looked after.
"We knew it would be a really tough Test match and in really tough Test matches you try to be as close to the line as you can be, but I don't think it was anything other than trying to put pressure on Johnny. But we have to protect our own players.
"We know we have Paddy to come on and perform really well, but you don't want players coming off unnecessarily."