He will need to maintain his form in the next round tomorrow against second seed and world No 10 Nicolas Almagro, who waltzed past last year's beaten semifinalist Santiago Giraldo 6-4 6-2. That's assuming the Almagro who can be one of the world's best players turns up, and not the one who left Auckland in 2010 facing accusations of tanking.
Either way, Kohlschreiber rates his chances.
"Almagro is a very hard hitter," he said. "[He's a] big server, very hard hitter. It's tough. You have to handle his power shots and you have to run a lot and bring back many balls to frustrate him to let him overhit the balls. But I think I have a good chance on hard courts."
Kohlschreiber was largely in control against Harrison today even though he lost the first set. He dictated the tempo of the match as he started to read Harrison's serve better, peppering the American's backhand and mixing things up by coming to the net.
He took an early lead in the third set and served out the match in two hours against a player tipped to be America's 'next big thing'.
"He has many years in front of him," Kohlschreiber said. "If I stopped now I know what he could do to improve but I will be quiet. He's already come far for his age."
Almagro will be a more difficult proposition. The tempestuous Spaniard couldn't get off the court fast enough in the hope of finishing his match in case rain interrupted, even changing ends with little break and showing his frustration when patrons were still milling about.
He won the second set in little over 30 minutes on the back of a strong serve (he won 86 per cent of points on his serve) and powerful forehand and didn't face one break point.
"I'm happy but tomorrow is another fight and I'll see what can I do," he said. "Philipp is a great player on this surface. He has a very nice backhand and he is serving very well, too. I'll need to play my best tennis."
Kohlschreiber played plenty in 2011, winning three titles and playing in another two finals, but all of his 10 titles have been on clay.
He will hope winning on a different surface isn't his mission impossible.
Meanwhile, sixth seed Thomaz Bellucci has lost an epic three-hour battle to Olivier Rochus in the Heineken Open tonight.
Belgian Rochus won the second-round match, which lasted three hours 12 minutes and included two tie-breakers, 6-7 (6) 7-5 6-7 (5).
Bellucci, ranked 30 places higher than Rochus at 37th, was a quarter-finalist in Auckland last year.
