SECOND ROUND LEADERBOARD:
-7 E Els (SA), D Love (US), DJ Trahan (US), B Curtis (US) - P Mickelson (US), K Na (US), R Goosen (SA) Selected others:-4 JB Holmes (US) -1 C Montgomerie (Sco) +1 M Laird (Sco), B Davis (Eng) +4 J Rose (Eng)
Els recovered from a slow start to move into contention
Ernie Els birdied two of the last three holes to card a second-round 69 and take a share of the lead at the Arnold Palmer Invitational at Bay Hill.
The South African had two bogeys in his first five holes, but four birdies around the turn transformed his round.
Els was joined on seven under by United States trio DJ Trahan, Ben Curtis and joint first-round leader Davis Love.
European Ryder Cup captain Colin Montgomerie shot a 71 to move to one under, but Justin Rose missed the cut.
After a first-round 75, Rose needed a much-improved showing to make the cut and boost his chances of Masters qualification, but two sixes in his first six holes effectively ended his chances.
Els' start was little better, but a run of three birdies in four holes moved him to six under, while Curtis recovered from two opening bogeys to birdie seven of 11 holes from the par-five sixth.
Love, who went 12 holes without a par in the middle of his round, was stunned to retain a share of the lead after a round featuring six bogeys.
"It was a little erratic," Love said.
"I made some pretty simple mistakes today that are a little more disappointing than yesterday's mistakes.
"I made a lot of nice putts, hit a lot of good shots, and obviously made a lot of birdies."
Phil Mickelson finished a shot back from the leaders after a 67 that featured an eagle two at the par-four eighth but also three bogeys in his first six holes.
The American, joined by Kevin Na and South Africa's Retief Goosen in a tie for fifth, said: "I have a tendency to have up-and-down rounds like that. But it's fun.
"I enjoy trying to create shots and hit shots and take on some of these pins and make birdies.
"Unfortunately, I tend to make a few mistakes at times."
Joint first-round leader JB Holmes fell to four under after a 74, but Montgomerie fared much better, recording four birdies to move into a tie for 29th.
However, few of his potential Ryder Cup picks had days to remember, though Italy's Edoardo Molinari hit a second successive 70 to move to four under.
Swede Henrik Stenson, who had led the European challenge hit a 78 to fall to one over, on the limit of the cut to make the weekend.