The Steelers' secondary gave up touchdown passes of 60 and 61 yards against Indianapolis after Haden left the game.
Pittsburgh sliced the deficit to 17-9 with 7:47 left in the third quarter on Roethlisberger's 7-yard touchdown pass to JuJu Smith-Schuster.
The Colts dominated for the first half of the game but failed to secure the 14-point lead they owned at one point in the second half.More news: TPP countries salvage agreement to keep trade deal alive
Ben Roethlisberger's 32-yard completion to Antonio Brown with 35 seconds set up a 33-yard field goal from Chris Boswell as time expired Sunday, giving Pittsburgh a 20-17 come-from-behind win at Lucas Oil Stadium. The extra point was blocked. And after Ryan Shazier picked off Brissett's pass at the Colts' 10-yard line, Roethlisberger scrambled long enough to find a wide open Vance McDonald for another 7-yard score early in the fourth.
The good news for the Steelers is that Haden is not necessarily out for the remainder of the season.
Joe Haden left the game in the first half with a leg injury, and Steelers coach Mike Tomlin later revealed that the starting cornerback will be out indefinitely with a fractured fibula.