LAS VEGAS -- Tom Byrum couldn't keep shooting 65s every day.
Byrum slipped with bogeys on the final two holes Saturday for a fourth-round 69 that dropped him into a tie for the lead with Billy Andrade in the Invensys Classic at Las Vegas.
On yet another perfect day for scoring in the desert, Byrum couldn't match the 65s he shot each of the first three days. But he played well enough to keep sole possession of the lead until missing the green on the final two holes to drop to 24 under.
Byrum finished with a 3-under 69, but in a tournament where birdies rule it was not enough to keep sole possession of the lead.
"I had a little struggling going on," Byrum said. "But I'm still tied for the lead and have a chance to win the tournament. So I'm very happy about that."
Andrade, meanwhile, shot a 5-under 67 to move into a share of the lead with one round remaining at a TPC Summerlin course that once again yielded birdies in bunches.
The two journeymen, both battling to win enough money to keep their PGA Tour cards for another year, led Scott McCarron by a shot, with Shaun Micheel one more shot back.
Phil Mickelson shot a 66 to get to 21 under, three shots off the lead.
Mickelson finished his round before Byrum, who shot 65 each of the first three days, came back to the field with his finishing bogeys.
"If I can get to eight, nine or 10 under tomorrow, I might have a good shot," Mickelson said.
It may not take that low a score, but Byrum was well aware of what might happen if he and Andrade try to protect a lead on Sunday.
"I wouldn't be surprised if we were sitting there watching each other and somebody blows by us," Byrum said.
Byrum, whose only win in 16 years on the tour came in the 1989 Kemper Open, is on the bubble as he tries to make the top 125 money winners and avoid a fifth trip back to qualifying school.
After making a winding 25-footer for birdie on the par-5 16th, he appeared ready to head into the final round of the 90-hole event with the lead. But, weary from the pace of a 5«-hour round, he 3-putted the 17th hole and made a bad chip from off the green on 18 for bogey.
"I just lost my feel. There was a little fatigue, and maybe my confidence went," he said. "I think I'll feel fresher tomorrow. It was hard to concentrate and focus on what I needed to do out there."
Andrade, who needs to cash some big October checks to get from his spot 159th on the money list into the top 125 exempt list, was feeling a little better about himself after getting in a tie for the lead.
He made no bogeys and five birdies, including a crucial 8-footer on No. 16 after Byrum had already made his birdie.
"I don't have a problem when I get in this position," Andrade said. "My problem has been getting in this position."
Andrade, who only three years ago was battling to get in the top 30 in this tournament, traces his troubles back to last year when he took a month off in May. He came back unable to score consistently and has struggled to find it since.
"No one wants to be in the position I'm in," he said. "You feel embarrassed. You know how good a player you are, you just haven't done it."
DIVOTS: Micheel, who shared the day's best round of 63 with Steve Lowery, came into this year with only $35,688 in career earnings. He is also trying to get in the top 125, and was 130th coming into the week. ... Byrum's streak of 297 tournaments without a win since 1989 is the fifth longest on the PGA Tour. ... The 24-under total is the best in the tournament after four rounds since 1991. In that year, Andrew Magee won with a tournament record 31-under-par.