This week's ATP Tennis action at Stuttgart and s-Hertogenbosh is now down to the quarter final stage. At Stuttgart on the ATP Tour top-seed Roger Federer got his campaign underway against teen sensation Taylor Fritz from the USA yesterday. The young American came very close to recording the biggest win of his career, but just lost 6-4 5-7 6-4.

Federer faces local hope and qualifier Florian Mayer today and the Swiss great leads the head-to-head 6-0, which include three straight sets wins on grass. With a competitive match on the surface now under his belt it's unlikely Federer will lose today, but at odds of around 1.15 I'd prefer to lay him given his unconvincing performance on Thursday and because Mayer is on a four match winning streak on the surface, including beating 2015 finalist Troicki in straight sets.

Philip Kohlschreiber (12/1) our one remaining outright selection at Stuttgart this week faces his toughest test to date against the in-form veteran Radek Stepanek, who knocked out second seed Cilic and leads the head-to-head 7-1, which includes there last encounter a straight sets win on grass at Eastbourne in 2015. Kohlschreiber clearly struggles to deal with Stepanek's unorthodox, attacking serve and volley game and with this in mind I advise covering your outright stake on Kohlschreiber by backing Stepanek at around 6/4 in the match market or in the outright market at 11/1 (1/3 odds a place).

Over at s-Hertogenbosch our one remaining selection Sam Querrey is through to the quarter-finals and faces compatriot Wild Card Stefan Kozlov, who is only 18 but has already recorded two impressive wins against more experienced higher ranked opponents Nishioka ranked 117 and compatriot Johnson ranked 39. Top two seeds Ferrer and Tomic are both still in action and Ferrer will face a stern test against veteran and seventh seed Gilles Muller while Tomic also faces a tough one against veteran eighth seed and defending champion Mahut, who is a grass court and serve and volley specialist.