INDIANAPOLIS – The Indianapolis Colts will be without their leading receiver for at least a few games. Michael Pittman Jr. is dealing with a back injury that will sideline him for Sunday’s game in Nashville against the Tennessee Titans and perhaps longer, according to a source with knowledge of the situation. The team still is evaluating the situation and a decision on how long Pittman might miss could be made later this week. Placing him on the injured reserve list – that means missing at least four games – hasn’t been ruled out. Pittman signed a three-year, $70 million extension in March that cemented his position as the Colts’ top receiver. The 2020 second-round draft pick has led the team in receptions and yards in each of the past three seasons. Pittman has gotten off to a slow start in his fifth year. He leads the team with 22 receptions but has been limited to 238 yards and one touchdown. Pittman had his best game in the week 4 win over Pittsburgh: six catches for 113 yards. He’s also been the most active. Pittman has been on the field for 87% of the offensive snaps (255). That’s the most by a non-offensive lineman. With Pittman out, the passing game must lean heavier on Josh Downs, Alec Pierce, Ashton Dulin and rookie AD Mitchell. Downs missed Wednesday’s practice with a toe injury. The last time Pittman missed a game, the Colts were unable to overcome his absence. Last season, a concussion kept him out of the week 16 trip to Atlanta, and the offense got very little done in a 29-10 loss to the Falcons. Gardner Minshew II passed for 201 yards and the offense finished with just 262 total yards. The wideouts combined for 10 catches and 77 yards. Downs finished with six catches and 39 yards. You can follow Mike Chappell on Twitter at @mchappell51.