The Open Championship at Royal Troon: Henrik Stenson

The Swede carded a second-round 65 to emerge as Mickelson's closest challenger at Royal Troon on Friday, cutting the five-time major winner's advantage to one shot.

Stenson has had a trio of top-three finishes at golf's oldest major, but knows overhauling Mickelson will be a tough task.

"Phil's not going to back down," he said. "He's got a number of majors already and he wants to have another couple, I'm sure.

"So he's not going to take his foot off the pedal. He's going to keep on trying as hard as he can and he's a great player.

"I've played a lot of golf with him this year. It feels like we've been out there every second week. I enjoy his company and I'm looking forward to the challenge.

"What does he have, five majors? Yes, it's going to be easier [for Mickelson] in that way. It's always harder to push the first one over the line, I would imagine, than the sixth one.

"But at the same time he's six years older than me, so I should be a little stronger, shouldn't I?

"We'll see if that has anything to do with it. But [there is] still a long way to go."