Webb Simpson believes he could be in career-best form after taking a share of the lead at the Rocket Mortgage Classic.

The American, who already has two wins this year, shares a one-stroke lead with Chris Kirk at the halfway mark of the PGA Tour event.

Alongside his victories at the Phoenix Open and RBC Heritage, Simpson – the 2012 U.S. Open champion – also finished third at the Sony Open in Hawaii.

Simpson believes he may be in the best form of his life, telling the Golf Channel: "I've been trying to become more well-rounded through the bag and I'm seeing results, having fun out there.

"Having Paul [Tesori, caddie] out there is great, we're not only having fun but we're really kind of in the same mindset, trying to get better both of us.

"We don't pause and stop and think and look around and see where we are enough I don't think, but I'm really happy to be playing well and have chances this weekend."

Simpson carded a bogey-free eight-under 64 in the second round to get to 12 under.

However, the 34-year-old sees room for improvement after managing to birdie just one of four par-fives.

"Normally par-fives are where I go get some birdies and these par-fives are gettable here," Simpson said.

"I didn't hit great shots into 14 or 17 after good drives so those are kind of a bummer to not get at least one of them.

"But at the same time I think it shows that I am making birdies, I'm capitalising on the par-fours and hopefully I can kind of turn that par-five performance around this weekend."