Bayern Munich not only lost its Bundesliga lead with a 2-1 loss to VfB Stuttgart, its Dutch attacker Arjen Robben suffered a calf injury that could keep him out of Tuesday’sChampions League quarterfinal clash with Manchester United. “It is too early to say whether Robben will make it,” said Bayern coach Louis van Gaal after his team’s 10-game home winstreak ended. “The doctors need to take a good look at his calf to see what’s wrong.”