"Because I served so well, my service games were relatively easy and it took so much pressure off me," he said. "It let me take a few chances on his serve.
"I feel like I'm playing well. If I keep serving well and keep hitting my forehand great, I feel like I'm a tough guy to beat. My goal is to win it but I've got to take it one match at a time."
His goal is also to break into the world's top 10 for the first time. He came into the tournament ranked 22nd in the world - he's been as high as 17 in January 2011 - and feels he has a good chance to do it in the first six months of the year given the ranking points he picked up in a good end to 2012.
The 25-year-old will now take on Canadian qualifier Jesse Levine, who beat Brian Baker 7-5 6-4, before a possible semifinal matchup against second seed and world No 19 Philipp Kohlschreiber.
Kohlschreiber, who won the Heineken Open in 2008, was stretched by Colombian Alejandro Falla before winning 7-6(4) 4-6 6-3 in two hours 12 minutes.
He won the critical points on the back of his experience and court-craft and is looking to carry on the good form of last year when he cracked the world's top 20 for the first time in his career.
The Heineken Open is his most successful tournament outside of Germany - he's won it once, been in the semfinals twice and only once failed to make the quarter-finals in eight previous visits here - but he has a tricky quarter-final against Belgian journeyman Xavier Malisse.