Mayer reached his career-high singles ranking of World No. 33 on September 27, 2004.
Mayer has reached two ATP singles finals in his career, both at Sopot. He lost to Gael Monfils in 2005 of France and Nikolay Davydenko of Russia in 2006.
At the 2004 Wimbledon Championships, Mayer reached the quarter-finals, which is his best Grand Slam result to date. He received the ATP Newcomer of the Year award in 2004.
Mayer is known for his unorthodox style of play. He has a long backswing on his forehand and backhand and uses a lot of different slices and spin on his backhand side. He is also known for his jumping backhand dropshots which catches many of his opponents on the back foot.
| Legend (Singles) |
| Grand Slam (0) |
| Tennis Masters Cup (0) |
| ATP Masters Series (0) |
| ATP Tour (0) |
| Challengers (5) |
| No. | Date | Tournament | Surface | Opponent in the final | Score |
| 1. | July 28, 2003 | St. Petersburg, Russia | Clay | Michal Mertiňák | 4–6 7–6 6–1 |
| 2. | March 15, 2004 | Mexico City, Mexico | Clay | Adrián García | 6–4 6–3 |
| 3. | June 5, 2006 | Furth, Germany | Clay | Torsten Popp | 6–3 6–1 |
| 4. | July 24, 2006 | Tampere, Finland | Clay | Ernests Gulbis | 7–6 2–6 6–3 |
| 5. | August 14, 2006 | Graz, Austria | Hard | Rainer Schüttler | 6–4 5–7 6–2 |