Well don't forget that Schuettler took out Guga in the first round. You could argue Guga didn't really try that hard to win it but Schuettler was suffering out there with the after effects of some illness (he had the doctor out twice during his match).
I think that match may well be the catalyst for his progress in this tournament. People say Coria has the most determination of any pro today.. well Schuettler must surely not be far behind. He never quits on himself and of course he has consistent ground strokes on both wings plus he's very fit and will run down everything. He may not have the most talent on tour but he does the simple things on a tennis court better than most pros there do it.. a prime example of someone whose playing the cards life dealt him rather than the cards he thinks he should have been dealt.