Colin Montgomerie sounded an ominous warning that Royal Troon will bare its teeth on Friday after shooting an even-par first round at The Open.

The veteran Scot, competing at what is likely to be his final Open, teed off the 145th edition of golf's oldest major in sunny weather on Thursday.

But the forecast shows rain and much higher winds for the second round.

"This hasn't shown any teeth, this course today," he said. "This is a three out of 10 job. Tomorrow we're talking seven, eight out of 10.

"It's going to be very different. I'm just glad I've got that 71 in there because I'll need them all."

The 53-year-old, who was runner-up at St Andrews in 2005, took a six on the par-four opening hole, but recovered to hit the turn three under.

After conceding all of the ground he had made up as he headed back in, Montgomerie said there was a huge difference in the difficulty of the front and back nine.

"I was three under on the front nine and three over on the back nine – that's par for both," he added.

"You'll hear players going three under, four under on the way out, then it's a matter of hanging in on the way back."

Asked about being the man teeing off the tournament, he said: "Fantastic. A great honour. It was a great honour for all three of us. Marc Leishman and Luke Donald both felt it. It was a great atmosphere on the first tee."