Sauers had consecutive birdies over Nos. 15-17 for a 3-under-par 67 that allowed him to pass the early leaders for a one-stroke lead at Royal Birkdale.
Those 10 were the only players who managed to beat par Thursday.
Sauers, at the tournament low limit of age 50, won three times in the PGA Tour but is looking for his first senior-level title.
He opened his round with nine pars. He birdied No. 10 but gave that stroke back with a 5 at the par-4 11th. His string of three birdies started at No. 15 and including a chip shot that lipped out at 16.
Langer, who won the Senior British Open in 2010, closed fast with three birdies in his final four holes. Minoza was 4-over after three holes -- he had a 7 at the par-4 third -- but was 5-under on the second nine, closing with four birdies in the last five holes.
Frost had two bogeys and two birdies before a 17th-hole eagle left him tied for second. Senior had four birdies and two bogeys on the day.