Wales lock Cory Hill has emerged as a major World Cup injury concern just 24 hours before head coach Warren Gatland names his squad for the tournament.

Gatland revealed after Wales' 22-17 warm-up defeat against Ireland in Cardiff that Hill has suffered a fractured in his leg.

The 24 times-capped Dragons forward has not played since scoring a try during the Six Nations victory over England in February.

He suffered an ankle problem during that game, and Gatland, who announces his 31-man World cup squad on Sunday, has delivered a fresh update.

"Our big discussion tonight is with Cory Hill," Gatland said. "He has got a fracture in his leg.

"It is a very small fracture which could keep him out until game two or three (of the World Cup) so that will be a big discussion on whether we take him or not."

It will be a huge blow for Wales if Hill does not go to Japan, especially given his performances last season, while he also captained Wales in two Tests against Argentina during their 2018 summer tour.

Gatland said there are "probably half a dozen positions" up for debate when he sits down with his fellow coaches on Saturday evening.

"It was a good exercise," added Gatland, reflecting on Wales' first home loss since November 2017.

"Some people put up their hand and made a good showing, and with others we had a few questions answered. It was good from that point of view.

"We will sit down tonight and it will take a few hours to finalise the squad.

"There are probably half a dozen positions that are really up for debate. Apart from that, we are quite comfortable with 24 or 25 players."

Asked if he thought it would be the best Wales squad he takes to a World Cup, Gatland added: "I think so, yes.

"I think it's the best squad in terms of the depth we've got.

"If we do pick up a few injuries like we did in 2015, I think we would be able to cope so much better now.

"The expectation from ourselves is that we will be very disappointed if we don't make the quarter-finals, and that's step one. Then you take every game as it comes.

"I think we've massively over-achieved in what we've done in the last 12 years.

"We are not finished yet. If we are mentally and physically right, we're capable of beating anyone in the world. I honestly believe we will go a long way at this World Cup."

Ireland's victory meant that Wales lost their number one world ranking to New Zealand, having reached the summit with a 13-6 victory over England two weeks ago.

Ireland suffered a record 57-15 drubbing at England's heads last Saturday, and head coach Joe Schmidt said: "I knew we were heavy-legged last week.

"I know we created a lot of angst for people outside the environment. We knew we would be a bit vulnerable, but it was still unacceptable to be that far off.

"So we restored a bit of self-confidence as much as anything this week.

"There will be more changes again, and next week (against Wales in Dublin) will be a whole different contest again."