Borussia Mönchengladbach goalkeeper Jonas Omlin has suffered a tendon injury in his lower leg during training this week and will be out of action “for the time being,” the Bundesliga club said on Thursday. “Treatment for his injury has already begun. It is not yet clear exactly how long the Foals will have to do without Jonas Omlin,” the club said in a statement. Omlin had started all Gladbach matches this season. Their next game is on Saturday at Eintracht Frankfurt in the Bundesliga. Despite two defeats in three league games, coach Gerardo Seoane said that “there’s a sense of optimism among …