In his only Grand Slam singles main draw appearance, Niemeyer reached the second round of the 2003 Wimbledon Championships by beating World No.

He also reached the Wimbledon doubles second round on two occasions, in 2005 partnering Glenn Weiner, and again the following year with Tuomas Ketola.

In late June he reached the semi-finals in both singles and doubles (partnering Emin Ağayev) at the Canada F2 Futures.

In February Niemeyer saw his first ever Davis Cup action, losing the deciding rubber in straight sets to Colombian Hadad Mauricio.

Two weeks again, Niemeyer was again with the Davis Cup team in a tie with a strong Bahamas, featuring Mark Knowles and Roger Smith.

The following week Niemeyer qualified for the main draw of the Binghamton Challenger, reaching the second round in both singles and doubles.

Three weeks later, Niemeyer won his first doubles title of his career, the U.S.A. F16 in Phoenix, partnering compatriot Jerry Turek.

Two weeks later, Niemeyer lost in the first round of qualifying, as the top seed, for Acura USTA Pro Tennis Classic at Mission Hills.

He won his first singles title the following week at the Champaign Challenger, winning a tight three-set final over compatriot and then No.

Niemeyer qualified for the main draw in singles at the Waikoloa Challenger in late January, losing 4–6, 2–6 to André Sá in the first round.

Niemeyer lost in first round qualifying action in singles for the U.S. Men's Clay Court Championships at the beginning of May.

Playing just singles, he reached the quarters in Tallahassee and lost in the first round at the USTA Tennis Championships of Denver.

In July at Granby, Niemeyer reached the finals in doubles, partnering Turek as an unseeded team, while he lost in the first round in singles as a wild card entrant, to Mark Knowles.

Niemeyer again attempted to qualify for the Legg Mason in Washington, D.C. and the Hamlet Cup in on Long Island but lost in the first round on both occasions.

The following week at France F18, the unseeded Niemeyer lost his only singles match and reached the second round in doubles, playing alongside Yves Allegro.

Niemeyer finally won a Challenger event singles match when he defeated Glenn Weiner in the first round in Knoxville.

He lost in the second round of qualifying in singles for the Dallas Challenger, he reached semis in doubles partnering Marcos Ondruska.

In April, Niemeyer again was called upon to play Davis Cup, in America's Zone Group I second round tie away to Argentina.

The following week saw Niemeyer be the Canadian Davis Cup hero, as he won the deciding rubber, in four sets, over Miguel Gallardo Valles of Mexico at the Chapultepec Sports Club, in zonal play-offs tie.

Niemeyer continued the same schedule as the previous summer, playing Binghamton, where he and partner Kokavec, unseeded, won the doubles.

Niemeyer's final action for 2001 came in doubles at Switzerland F3, where with partner Yves Allegro, as top seeds, he reached semi-finals.

Again not attempting to qualify for the Australian Open, Niemeyer next competed at the Dallas Challenger reaching the second round in singles, going out in three close sets to top seed Cecil Mamiit, and won the doubles, partnering Giorgio Galimberti.

The following week in Davis Cup, Canada defeated Mexico in Waterloo, Ontario on carpet, as Niemeyer took the opening singles rubber as well as the doubles match, partnering Daniel Nestor for the first time.

The following week, also on clay at the ARMS USTA Challenger, in Rocky Mount, North Carolina, Niemeyer again lost in the first round in singles and the semi-finals in doubles, playing alongside Cecil Mamiit.

Niemeyer returned to North America to play Granby for the sixth consecutive time, matching his singles result of the previous year, losing in the semis to World No.

For the fifth straight year Niemeyer received a wild card into the main draw of the Tennis Masters Series event in Canada, and again failed to get out of the first round, this time losing to No.

Not playing Binghamton this year, Niemeyer lost in the first round of the Bronx Classic in both singles and doubles the following week.

Niemeyer fell in the final qualifying round at Wimbledon to Izak van der Merwe after having defeated two higher ranked players, Harel Levy and Lukáš Dlouhý in the first two.

Not surprisingly, he and Nestor won their doubles rubber, and he was called into singles action when Peter Polansky became ill, but lost in four sets to Luis Horna.

Niemeyer defeated Samuel Groth in the first round singles qualifying for the ATP 250 event in Indianapolis by a score of 6–4, 4–6, 7–6(11–9).