Padraig Harrington, feeling refreshed again after a draining summer, carded a respectable one-under-par 69 in the opening round at the BMW Championship on Friday.

The Irishman has missed the cut the past two outings but he was understandably jaded after winning the Open and PGA Championship only three weeks apart, and he admitted his main priority now is to have his game on song for the Ryder Cup in a fortnight after he finished the day four strokes behind Colombian leader Camilo Villegas at Bellerive.

"I had a nice chance at the last for birdie from six feet. If I'd shot 68 I would have been very happy with my day but 69's okay," Harrington said. "There's a bit of a kickback from that and you have to accept it," he said of the post major letdown."

He added: "I'm experienced enough in this game to understand there are ebbs and flows. The main thing is to make sure you peak at the right times during the year and I've got better doing that.

"It's inevitable if you do try and peak you'll have a bit of a dip afterwards. I'm trying to hang on (for the Ryder Cup).

"My schedule was set out this year so I would peak again for the Ryder Cup but I didn't envisage having so much drama in the middle of the season."

Harrington needs to finish at least 10th this week to have even a mathematical chance of advancing to the 30-man Tour Championship in three weeks.

Meanwhile, Villegas bogeyed his final hole, but his 65 was still good for a one-shot lead over Americans Steve Stricker, Kenny Perry and Tim Herron, Australian Stuart Appleby and Argentinian Andres Romero.

"I hit a lot of great shots out there, gave myself a lot of birdie putts," said the 26-year-old from Medellin, via the University of Florida.

"Unfortunately I finished with a bogey but I'll be back and hopefully put another good number on the board."