After upsetting world No. 1 Novak Djokovic in Miami, Tommy Haas said it was about as high a level of tennis as he has ever produced.

“I have had some good results last year,” Haas told reporters. “Probably in Halle maybe where I won the tournament. You go back to obviously where you maybe have won matches against top players like against Roger [Federer, who Haas upset in the Halle final], maintained a really high level. It’s tough obviously. It’s one of the biggest challenges out there. You know, even looking at Novak Djokovic’s results the last two years, two and a half years, it’s just crazy. You look at Roger last eight, nine years, and [Rafael] Nadal, how tough they are and maintaining that level. It’s something really special. Not everybody has that gift. So I’m happy to have done it somehow a little bit tonight.

Haas, who will turn 35 next week, says he couldn’t have imagined still playing at this level after multiple injuries and surgeries.

“There were times I wouldn’t have believed that, no way,” the 18th-ranked German said. “But when I came back after my hip surgery it was a grueling, I don’t know, nine months, 12 months before I actually felt like I can sort of train again and get in better shape and sort of maybe feel like I can move and give myself a chance to at least try to go for some victories again that I would enjoy. Somewhere in the middle of last year, sometime in April, May, my body sort of adjusted a lot, got better, and I could train. If you can’t train and put in the hard yards in this sport anymore, you’re not going to get far, not at least to the point where maybe you have a chance against a top player. Right now I feel pretty good, as good as I have in a long time, and just never give up.”