Cape Town - Viktor Troicki and Lucas Pouille were both knocked out of the Mercedes Cup on Tuesday.Sixth seed Troicki was ousted by Florian Mayer 6-4, 7-6(4) while Australian John Millman came back from a set down to defeat eighth seed Pouille 6-7(3), 6-3, 6-4 in a touch over two hours. The win for Millman books him a place in the second round where he will face former US Open winner Juan Martin Del Potro. The Argentine, who is playing his first event since the Mutua Madrid Open, eased past Grigor Dimitrov in straight sets 6-4, 6-2. He fired 12 aces and dropped just ten points on serve in a solid display.Meanwhile, 18-year-old Taylor Fritz came back from a set down to edge Fabrice Martin 3-6,l 7-6(6), 6-1. The win books the American a date with top seed Roger Federer in the second round, who returns from a back injury sitting out Roland Garros.