Kai Brünker’s stoppage-time goal sent third division Saarbrücken into the German Cup semi-finals with a 2-1 win over Borussia Mönchengladbach, their third Bundesliga giant-killing after toppling Bayern Munich and Eintracht Frankfurt. Robin Hack gave mid-table Gladbach an early lead on Tuesday after Franck Honorat’s pull-back but Amine Naifi levelled for the hosts on 11 minutes with a fierce strike from 18 metres. The mid-table third-tier side defended stoutly, although the Foals failed themselves to find that killer pass, and the game looked to be drifting to extra-time. But up popped Brünker …