The San Francisco 49ers placed star running back Christian McCaffrey on injured reserve on Sunday, ensuring last season’s NFL rushing leader will miss at least the next four games. McCaffrey missed Monday night’s 32-10 win over the New York Jets with an Achilles tendon injury causing calf pain. The move, which comes a day before the 49ers play the Vikings in Minnesota, means he won’t be eligible to return until the team’s October 10 game against the Seattle Seahawks. After saying earlier in the week that he didn’t envision McCaffrey going on IR, San Francisco coach Kyle Shanahan said Friday said the team would reconsider after the pain flared up after McCaffrey’s limited participation in practice. “It’s on and off, but with (Thursday) having the most pain. It’s something we’re going to be discussing together in the next 24 hours.” McCaffrey says the injury has nothing to do with the calf injury he suffered late last season, and as recently as Wednesday he’d told reporters he was preparing to play against the Vikings. “I hate not playing,” he said. But the injury has been unpredictable, and the team will be hoping an extended period off will allow McCaffrey to be at full strength for the majority of the season. “He’s dealing with this Achilles tendinitis, which can be one of those deals where it’s feeling good one day and the next day it flares,” general manager John Lynch said in a radio interview on Friday.