The German, who shared the overnight lead with Mark Wiebe, carded five birdies and a single bogey in a round of 66 to sit nine under overall.
Langer already has a Senior Open title under his belt, from Carnoustie in 2010, and would welcome another in his trophy cabinet.
"It's always special to win any tournament, but to win a Major and to win it on a golf course like this, would mean a lot," he said on www.europeantour.com.
"There's a lot of golf left. We all know that. There's somebody inside me that expects me to win, but I know there's 18 holes left, and there's a lot of shots to be pulled off and a lot of putts to be made. So golf is not over til it's over, and we've got 18 holes to play."
Langer was the outstanding performer on a leaderboard which saw a number of changes from on Friday.
David Frost climbed into second place with a round of two-under 68, one shot ahead of Wiebe who mixed two birdies with as many bogeys in his score of 70.
The 55-year-old American remains on five under for the tournament and is now four shots off the lead.
Sandy Lyle climbed the standings with a one-under 69 round to sit alongside Peter Fowler and Gene Sauers on three under for the tournament.
Australian Fowler and Sauers of the United States both carded level-par 70s today to slip off the pace.
England's Gary Wolstenholme crept on to the leaderboard with a two-under 68, which included four birdies on the back nine, although he sits nine shots behind Langer.
Colin Montgomerie also improved on his previous scores of 72 and 71 with a one-under 69 to move up 10 places into a four-way tie for 13th on two over.