The goal-kicking loose-forward was being assessed by Rhinos' medical staff today after injuring a knee in last night's dramatic 23-22 defeat at Wigan Warriors.

Rhinos – who had trailed 23-6 after an hour – had a chance to win the game in the final seconds, but stand-in kicker Rob Burrow was narrowly off-target with a long-range penalty attempt.

The injury to Sinfield is a major concern for Rhinos, but coach Brian McClennan is hopeful the player won't be out long-term.

"It will get assessed better today, but we are thinking medial ligament strain," said the boss. "Fingers crossed that it's just a strain and hopefully not too big a one. He couldn't put much weight on it and he had to come off.

"We're fortunate we've got very good medical staff at the club and Kev's a consummate professional, he'll do everything right in his re-hab to make sure he's okay."

Last night's defeat was Rhinos' third in four games and they will be knocked off the top of engage Super League if St Helens beat Harlequins by 32 points tonight.

McClennan said: "We were involved in what will be regarded as a great game to watch, because it was so close.

"There was some good footy played out there, but it's tough to take because you like to win those close ones.

"I wouldn't put it down to the missed kick, it was more our first 20 minutes.We were a bit indisciplined and that's something we've got to improve on. It was getting down 16-0 that cost us the game.

"Rob's a fantastic player. I'm disappointed in a way that he was put in that position. It shouldn't have been like that, we could have done a lot better at the start.

"It was a good effort, we just need to start our games a bit better."

McClennan added: "We gave away penalties and too much possession in the first half.

"We weren't able to get to that second wind period and our attack faltered, but over the whole game I think we made enough splits – we split through quite a few times – but we lacked that support that we usually have.

"It's a matter of us getting back and training hard and moving on from here."

Burrow will have no qualms about continuing kicking duties if the injury keeps Sinfield out.

The scrum-half said: "It wasn't far off, but there's no excuses – it missed, simple as that.

"I am more than happy to take any penalty, anything like that. It's something that happens and I'll knuckle down and put in a bit more practice."

Burrow described Rhinos' overall performance as "scratchy", adding: "There were too many errors and we put ourselves under the cosh. We left it late. We were 17-0 down at half-time and we've got to start a lot better.

"We've got a really spirited team and an exciting team on attack. We aren't a team that's ever going to give in and just lie down, but sometimes you give yourselves too much to do and you can't always come back and win them.

"Wigan are a great side anyway, without giving them a head start. We've got to put that right.

"It's getting towards the end of the season and the important games and we want to be firing by then, not dropping off form."

Tryscorer Gareth Ellis admitted Leeds were second best for most of the game.

"We were disappointed with how we played," he said. "We came on strong in the second half and the way we fought back was a credit to us, but we can't give teams a head start like that.

"Time ran out for us otherwise we might have just got there, but that's the way it goes.

"Looking at the game, I think Wigan would have felt hard done by if they hadn't got the win."