Sam Torrance carded a third-round 71 to keep the Scot's hopes of US Senior Open glory very much alive at Whistling Straits.

Torrance collected four birdies and three bogeys in his one-under-par effort to move into a three-way tie for third place on three under, four strokes behind leader Tom Watson.

The 54-year-old, who captained Europe to Ryder Cup Glory at The Belfry in 2002, played the opening nine holes in level par before bogeys at the 16th and 17th spoiled what would have been a second consecutive 69.

Watson overcame some early struggles to shoot a one-over-par 73 and maintain his three-stroke lead over Loren Roberts, who also carded a 73, on seven under par.

Six players remain within striking distance on two under, including Senior PGA Championship winner Denis Watson, who carded the best round of the day with a 67.

Des Smyth's challenge faltered in the third round after a 78 dropped him back into the pack.

Starting the day with a three-stroke advantage, four bogies and just one birdie over the front nine saw Watson fall into a tie at the top of the field.

However, a birdie on the 10th coupled with a 15-foot birdie putt at the 16th saw the 57-year-old pull clear and leave him in confident mood ahead of Sunday's final round.

"If I play a good round tomorrow, I should win the tournament," Watson said. "Unless somebody really goes out and shoots a no-brainer, which can happen on this Tour. It feels good to be the leader, especially after the front nine.

"The back nine was a struggle but I made a couple of birdies, saved a couple of pars from awkward places and I was grateful to be in the lead."