Tony Adamson reports for BBC Racio 5 Live

The Scot fired a five-under-par 67 to move ahead of his two rivals for the European crown, Lee Westwood and Darren Clarke, at the half-way point of the last event of the season.

Westwood added a 68 to his opening 70 and looked to be about to take the advantage in the three-way tussle.

But two late eagles and an even later birdie put Montgomerie, who leads the European rankings, in charge of his own destiny at seven-under-par - one stroke ahead of Westwood.

Struggling: Clarke tries to get out of trouble

But Australian Peter Lonard is in control of the event, after scoring a 66 to move to ten-under for the tournament - three shots clear of second-placed Montgomerie.

Clarke's outside chances of taking the Order of Merit faded in the second round.

The Ulsterman is in third place behind Westwood in the rankings and he has to win the Volvo Masters and hope his rivals slip up.

But having taken a share of the first round lead with a 67, Clarke slipped back into the pack with a second day 73 and is now in tenth place at four-under-par.

Monty gets into the swing

"This is fun now," said Montgomerie, clearly enjoying the battle for supremacy in Spain.

"At the start of the week I hoped that three people would finish ahead of Lee and one ahead of Darren. That way it didn't matter what I did.

"But now I feel I have to take care of it myself rather than rely on others - and I relish that.

"I like a challenge and I have one here. I am just a very competitive person and I think competitive people work better when it gets tense, which this is now.