Tiger Woods and Rory McIlroy both fancy their chances of winning the US Open this weekend - and they could continue their challenge in the same group for a third day running at Merion.

The world's top two players shot matching rounds of 73 and 70 to reach halfway at three over par, four shots behind clubhouse leader Billy Horschel.

"I'm very happy," said McIlroy, who before this week had played 13 competitive rounds in the same group as Woods and only twice shot a lower score.

"I'm right in there for the weekend.

"I don't think I'll be too far away by the end of the day, in a nice position going into the last two days."

Asked if he liked his chances of a 15th major title and first since 2008, Woods simply said: "Yes."

And the world number one was equally brief when asked about seemingly being in pain when hitting shots from the rough, saying only that he had hurt his left elbow during his win at the Players Championship last month.

As for his round, which contained three birdies and three bogeys, Woods added: "I played well. I just made a couple of mistakes out there today, but I really played well. Maybe I could have gotten one or two more out of it, but it was a pretty good day.

"You just don't ever know what the winning score is going to be. You don't know if the guys are going to come back. We have a long way to go and these conditions aren't going to get any easier. They're going to get more difficult.

"As the fairway starts drying out, the ball is going to pick up mud, and you're going to get bad breaks."

McIlroy and Woods get on well - and play with the same equipment since the Northern Irishman's controversial multi-million pound switch to Nike in January - but McIlroy joked: "I told him on the last there that I was trying to hole the putt, so I didn't have to play with him again tomorrow.

"It doesn't change that it's a US Open or whatever. We still get on well and there was still a good bit of chatter out this and a good bit of needling every now and again."

McIlroy will fly the flag for Ireland with Padraig Harrington and Kevin Phelan at the weekend after Graeme McDowell and Darren Clarke missed the cut on 13 and 15 over respectively.

"It's unfortunate that Darren and G-Mac aren't here for the weekend, but I'll do my best to try to bring that trophy home another time," said McIlroy, who won by eight shots at Congressional in 2011.

"I feel like I've been playing well. I've been telling everyone for a while that the game is getting there and to get through two rounds of the toughest test at the US Open and play the way I did, it's very promising going into the weekend."

Former champion McDowell, who had been strongly fancied thanks to two wins this year and a superb US Open record, said: "I'm temporarily dejected.

"I'll shake it off and I'll get ready for the Open Championship in a few weeks' time. That's my next target. I struggled the last couple days, but that's golf and that's the US Open."

The rough, nourished by a week of rain, caused havoc for a bunch of former U.S. Open champions, including Angel Cabrera of Argentina, who shot an 81, and American Jim Furyk (79) and McDowell (77).

It's that hard, it's that difficult, it's that long," said McDowell, who had a 36-hole total of 13-over 153.

"I'm disappointed, of course. It's not the way I wanted to play the last couple of days. But this place is very hard."

There were 69 double-bogeys and 13 worse scores with players averaging rounds of five-over-par 75.