55-year-old Kelly had six birdies and a bogey to match Cejka at nine-under on Firestone Country Club's South Course.
"No 1, getting the ball in the fairway, so I can have control of my irons," Kelly said. "Not trying to do too much with my iron shots, just giving myself good looks. And then the putter was better today."
Cejka birdied four of the last five holes for a 67. The 51-year-old Czech-born German is chasing his third senior major title after winning the Regions Tradition and Senior PGA last year.
"It's great to finish strong," Cejka said. "I played pretty good all day long, but had a terrible start, made two stupid bogeys. Had a lot of good chances, couldn't make a putt with great shots. It's frustrating."
Defending champion Steve Stricker (68) is tied with Alker. Ernie Els (69) is a shot back at six-under.
Elsewhere, Ryan Fox heads into the final round of a stacked Scottish Open field in a share of 61st place after a three-over 73 saw him fall back to five-over on the card at The Renaissance Club in North Berwick.
The Kiwi is 12 shots behind American Xander Schauffele who had a two-shot lead at seven-under.
On the PGA Tour, Josh Geary is tied for 61st with rain disrupting play during the third round of the Barbasol Championship in Kentucky.
Geary only played nine holes before play was suspended, with the leaders having only played three holes and facing a long day tomorrow.