By Ken Brown BBC Sport golf commentator

Justin Rose leaked nine shots in the third round on Saturday

The saddest story of the day was undoubtedly the unfortunate round of Justin Rose, who started the day with a two-shot lead.

He finished with an 81 and things started to go wrong right from the start of his round.

He got a bogey at the first but that is not the end of the world because it is a tough par four - it was the second hole that saw the start of his slide.

After finding himself in the trees he played out too near the green and left himself a difficult pitch.

He thinned that and it set the tone for the rest of the day.

He immediately bogeyed the third and once things go wrong that early you start chasing pins.

Although it was very sad he handled himself perfectly - there was no banging of clubs.

He will learn something from it but it was almost difficult to watch.

The star man of the day was Phil Mickelson, who produced a very controlled round of 69.

Mickelson has played some brilliant golf but winning your first major is not easy American duo lead Masters

It was a slightly different Mickelson because he was not trying to hit the ball too hard with his irons.

He played within himself and of the two leaders he looked to have the ball more completely under his under control.

He has had chances to win the Masters before and he ought to be able to win at Augusta because the course suits his game perfectly.

His co-leader, Chris DiMarco, has now played two rounds - the first and the third - without dropping a shot and although he would be a surprise winner he is fully capable.

The upside for the British was Paul Casey, who produced a tremendous 68, which was the second-best score of the day.

He was at Arizona State University, where he broke Mickelson's stroke-average record, and he seems comfortable with all the things that go with being a professional golfer.

He has inner confidence and he reminds me a bit of Tony Jacklin, who was also very self-confident.

Casey played one of the shots at the day. It was from the left-hand bunker at the 18th and was reminiscent of Sandy Lyle's when he won back in 1988.

If anything it was even better than Sandy's, although he was not under quite the same pressure!

Mickelson has a great chance to finally win his first major

It was just a shame he then missed the putt.

Two-time champion Bernhard Langer also played very well and no-one knows the course better than the German.

The European Ryder Cup captain sank a superb long putt at 11th and followed up with a lovely putt at the 15th for his eagle three.

He played some tidy golf to put himself in contention for victory and if he does go on and win the tournament, which is a possibility, it would almost guarantee him a place in the Ryder Cup team.

If he makes the team he will probably play and they would have to find another captain, which could cause something of a dilemma.

Thunder and rain is forecast for Sunday so play will start an hour earlier.

The winner has come from the final two-ball for the last 13 years but I've still got a little inkling that if Ernie can have a straight-driving day then he could challenge.

Mickelson has played some brilliant golf but winning your first major is not easy, particularly when you are under added pressure because you have not won one despite knowing you are good enough.

So he will have plenty of pressure anyway, even without Ernie putting on even more.

Final-day pins can be very tricky and the greens will be fast, although that depends on whether any rain falls overnight - they are expecting isolated storms which may or may not hit the course.