Colin Montgomerie aces the 17th and claims four-shot lead in Mauritius

Colin Montgomerie produced an astonishing finish to his second round to open up a commanding lead at the season-ending MCB Tour Championship in Mauritius.

Montgomerie enjoyed a superb hole-in-one at the 17th in between birdies at 16 and 18 which capped a flawless eight-under 64 and swept him four strokes clear of the field on 12 under par.

The eight-time European No 1 kept himself in touch with overnight leader David Frost as he cruised to the turn in 34, and birdies at 11 and 13 lifted him to eight under - one behind the South African.

But as Frost stumbled with a double-bogey at the 15th, Montgomerie rolled in his fifth birdie putt of the round at 16 and then nailed a perfect eight-iron to the 164-yard 17th hole.

The Scot signed off with another birdie at the 18th to cap a faultless performance, and he said: "When you drive the ball well on this course and keep it in play from the tee, you're likely to have a good day out there - especially as my iron play is my strength.

"I think I hit 16 greens out of 18 today and managed to take a few birdie chances, then of course the 17th was a bit of a bonus. Normally I hit my eight-iron 158 yards, so I was on the limit but the wind was helping us slightly.

"I struck it very nicely, then it got a kindly bounce and started tracking towards the hole, so at that point I started getting a little excited. You always hope it's going to drop in but of course it rarely does, so it was very nice to see it disappear from view.

"That finish sets me up very nicely for tomorrow, I've given myself every chance of finishing the season on a high note and that's what we'll try to do. But it won't be easy, we all know from past experience David is a great competitor and he loves it round here, so I'll have to play very well to win."

Frost, who set the first-round pace with a 63, maintained his lead after he recovered from a bogey at the second with three birdies in five holes, and another at the long 13th got him to 10 under.

But he then found water from the tee at 15 and ran up a costly six, and although he got one back at the next, he dropped another shot at 17 to slip four behind Montgomerie and admitted afterwards that the intense heat had contributed to his scrappy finish.

European Seniors Tour Golf

"I hit a couple of loose shots on the way in, maybe I got a little conservative but it's difficult to concentrate fully in the heat," said Frost. "I got a little light-headed and a little dehydrated, so that's probably cost me in the end but I'm still in with a good chance on the final day.

"I'm probably going to have to go low, but you never know what can happen in golf. I've got less to fear and nothing to lose, so I'll set out aggressively and try to put some pressure on."

Frost's compatriot Chris Williams earned himself a place in Sunday's final pairing with Montgomerie as he carded three birdies in four holes from the third and added another at 13 before parring in to complete a bogey-free 68.

England's Barry Lane, runner-up in the season finale last year and in 2012, chipped in for eagle at the last to return a 66 which lifted him to seven under, 

Barry Lane also put himself in position to win the season finale for the first time, having finished runner-up in last year and in 2012, while fellow Englishmen Andrew Sherborne (70) and Paul Eales (72) are both seven shots adrift of the leader.