CROMWELL, Conn. — Phil Mickelson’s attempt to become the first 50-year-old to win a PGA Tour event since 2015 and only the ninth to ever do it took a turn for the worse Saturday, as he lost the lead he took into the third round of the Travelers Championship.

Mickelson, who turned 50 on June 16, was unable to build on the 64-63 start the first two days and shot a disappointing 1-over 71 Saturday to leave himself at 12-under — six shots out of the lead held by Brendon Todd.

“I was a little off today, but I’m having a lot of fun,’’ Mickelson said. “This has really been a lot of fun. I haven’t played great this year. I’ve missed a lot of cuts, and the next thing I know my game is starting to come back and I can sense it.

“I’m going to come out [Sunday] and give it my best to go low. I know I’m playing well enough to do that. I think I’m going to continue to start playing better and better as I continue to work on a few things.

“We all have days where we’re just a fraction off, where you think you hit a good shot and it doesn’t quite work out, and I felt like I had one of those days. Then usually the next day, you come back out and you put it all together. So, it’s not far off.’’

Another day, another coronavirus incident.

On Saturday, though, there were no more withdrawals after the seven that took place the previous three days. But Jason Day requested a COVID-19 test prior to the third round at TPC River Highlands. He tested negative and played by himself with a 9:15 a.m. tee time off the 10th hole.

The 32-year-old Australian was originally scheduled to play at 8:09 a.m. in a threesome that included Rafa Cabrera-Bello and Roger Sloan. Because he had to wait for the test results, Day was re-assigned to play as a single as a precautionary measure as part of the PGA Tour’s health and safety protocols.

While he missed the cut at both the Charles Schwab Challenge and the RBC Heritage the previous two weeks, Day began Saturday’s third round at 4-under after shooting 67-69 and in a tie for 53rd. He shot a 1-under 69 Saturday and is tied for 49th.

It’s unknown whether Day felt COVID-19 symptoms overnight as Denny McCarthy did before testing positive before Friday’s second round and withdrawing. It is believed Day requested the additional test because of the McCarthy positive test and because he’d been around McCarthy at some point during the week.

The tour said Saturday that all follow-up tests from potential contact with McCarthy were negative.

In light of three positive tests at the Travelers this week (Brooks Koepka’s caddie, Ricky Elliott, along with Cameron Champ and McCarthy), the Tour announced another update to its testing program to further encourage players and caddies to adhere to on-site protocols.

Effective with the Rocket Mortgage Classic next week, players and caddies, along with all other individuals “inside the bubble,” will not be allowed on golf course property until first being cleared with a negative in-market test.

Previously, players and caddies could be on site to practice as they awaited their arrival testing results, but without access to any indoor facilities.