Rory McIlroy carded a second-round 68 to move on to five under par at the US PGA Championship - three strokes adrift of leader Matt Kuchar.
Third at The Open last month and in this event last year, McIlroy said: "I'm in a great position and I can just go out and play some good positive golf. I like the position I'm in."
Darren Clarke was the European who at the start of the day was best placed to challenge, three under with five holes of his first round to come.
Instead he had three bogeys and then a double bogey for a 74, but battled back to level par with a 70.
After starting with a 75, Padraig Harrington covered the first six of his second round in a superb three under to get back to level par - but Shane Lowry could only manage a 79 and is six over.
Following another delay for fog at the start of the day, 78 players will complete their rounds on Saturday morning.