US Senior Open: Colin Montgomerie leads by one shot ahead of Scott Dunlap

Colin Montgomerie leads the US Senior Open by one shot after carding a second round of 71 at Oak Tree National in Illinois.

The Scot remained on six under for the tournament, holding onto his advantage despite only managing to shoot level par on Friday in Oklahoma.

Montgomerie, who won the Senior PGA Championship earlier this year, dropped two shots over the first six before staging a recovery.

"It's never easy leading. I was two-over after six (holes) and got back it back to level for the day. It was very easy to let that go today," he said.

Scott Dunlap is hot on Montgomerie’s tail on five-under-par after adding a blemish-free second round of 68 to his opening effort of 69.

Gene Sauers carding an eagle, three birdies and three bogeys in a rollercoaster round of 69 which left him on four under for the tournament.

"I have been particularly good with the putter this week, made all my short ones," Dunlap said.

He added: "At this age, you know, the more I hit balls, the more my left thumb or left wrist I feel - I have got friends that are the golf equivalent of basketball gym rats. That works for them. It doesn't work for me."

Bernhard Langer is alongside him in third place having also carded a second round of 69 which included six bogeys and four birdies.

Marco Dawson, who was one shot behind Montgomerie after the opening day, dropped well down the leaderboard after shooting a second round of 76.