WARREN Gatland is mulling over changes to his side for Italy after labelling Wales' lethargic first half display at Twickenham as unacceptable.

The Six Nations clash with the Azzurri would have been a title coronation had they triumphed against England but instead it will be a subdued affair.

Wales are huge favourites to record a third home win of the campaign against an Italy side fresh from a hammering in Ireland and the pressure will be on to rack up the points after a hugely disappointing display in London.

Wales saw their title hopes go up in smoke after being beaten 25-21 at Twickenham, leaving their charge too late after heading into half-time 16-0 down.

Gatland was at a loss as to how his charges were so lethargic for much of the Test given what was at stake and is now poised to tinker with hooker Ken Owens, lock Luke Charteris and scrum-half Rhys Webb likely to be in the mix for a promotion from the bench while fly-half Rhys Priestland also made an impressive cameo.

The likes of back row Ross Moriarty and Newport Gwent Dragons wing/full-back Hallam Amos will be hoping to force their way in for Six Nations debuts.

"I gave them a rev up at half-time and said you need some enthusiasm, some energy out there," said the New Zealander.

"I spoke in the box, sent the message on after 25 minutes: 'do we need to make changes and get some fresh legs on?'

"It was really unlike us, it was a really poor first 40 minutes. England had something like 80 percent territory and possession.

"But then we showed what we are capable of doing in the second half. It was a game of two halves. I have said to the players only they can answer that question why they were so flat or lethargic in that first half because we have trained well all week.

"It was a massive game, so much to play for, so much on the line and unfortunately we didn't turn up for those first 40 minutes."

"We prepared the same as we normally do," he continued. "I have said to the players about being honest about why we were so flat at the start.

"At this level it is just not acceptable as far as I am concerned, it is very disappointing. We did rectify things, we scored three tries to one and played some pretty good rugby in the second half."

With a three-Test tour to New Zealand looming, Gatland may take the chance to look at some fresh faces.

"I thought some guys came off the bench and did a really good job for us," he said. "Ken Owens was outstanding in the way that he carried the ball and gave us some go-forward.

"We need to look at potentially an opportunity for players and continuing to develop the depth of the squad as well.

"It may be a case of making a few changes but we've also got to be smart in how we do things because if England beat France to win the Grand Slam then we are playing for second."

Captain Sam Warburton was stretchered off after being caught in the head by the boot of lock Alun Wyn Jones. The flanker was sitting up in the changing room afterwards and will be monitored by the medical team.