London - Leigh Halfpenny admitted his legs were "killing" him as he stepped up to take the penalty that sealed Wales's 13-6 win over England on his return to Test rugby after a prolonged absence due to concussion.
The 30-year-old fullback -- who missed the Six Nations Grand Slam campaign -- only played because coach Warren Gatland did not want to risk Liam Williams ahead of the start of the World Cup in September.
Williams had pulled up in the warm-up on Saturday with a tight hamstring and Halfpenny, having not been in the matchday 23, was asked to step in.
Halfpenny -- who was concussed following a late tackle from Samu Kerevi during Wales' win over Australia in Cardiff last November -- produced a solid performance, capping it with the penalty that ensured Wales went top of the world rankings for the first time in their history.
"He is absolutely shattered! He said to Alun Wyn before he kicked that last penalty, 'my legs are killing me'," said Gatland.
Halfpenny, who has been capped 81 times by his country since making his Test debut in November 2008, had undergone a full session on Saturday morning.
"I'm not going to lie -- we had a couple of tough sessions in the last couple of days," said Halfpenny.
"But you get the call, and that adrenaline just kicks in. It's an opportunity to put that jersey on.
"On Friday, we had speed endurance training.
"We did Broncos, which are basically shuttles, and the boys put it in on Friday after the captain's run.
"Then on Saturday morning I had leg weights followed by a watt bike session in the altitude room. (I) wasn't walking too well, I will be honest."
Halfpenny, who also has four British & Irish Lions caps to his name, said he had made huge efforts to regain his fitness so he would play for his country again.
"You never know when it could be the last time that you wear that jersey," he said.
"You just keep working hard. It was a real tough Test match, and the boys dug deep at times when we needed to. It was a great result.
"We've got that momentum going now ahead of our (training) camp in Turkey. The boys will be putting the hard work in again."
Wales's medical staff will assess the status of several players prior to leaving for Turkey.
Injury-plagued flanker James Davies suffered a concussion, Jake Ball and Aaron Wainwright suffered dead legs, while man-of-the-match Dan Biggar took a knock and had a tight groin.
The Welsh -- who are bidding to improve on their best World Cup performance under Gatland of reaching the 2011 World Cup semi-finals -- wrap up their preparations with a double-header against Ireland in Cardiff on August 31 and then Dublin on September 7.
They begin their World Cup campaign against Georgia on September 23.