Tomas began playing tennis when he was five years old in his hometown Valasske Mezirici. In the short term he worked his way up to the top of junior tennis ranking. After winning the Czech Championship in the cathegory of younger children he transfered to Prostejov tennis club where he could find more advanced training partners and better management too. After years of hard training Tomas also won the prestigious Championship of older adolescents which takes place in Pardubice and whose winners include Ivan Lendl.
Tomas became a professional player in 2002 when he jumped over 800 places up in the ATP ranking and won two Futures.
In 2003 he debuted at the US Open where he as a qualifier reached the second round of the main draw on his very first Grand Slam. In the same year he joined Czech team in the World Group play off of Davis Cup against the Thailand. In his first match, double with Jiri Novak, they won and the next day he defeated in the deciding match Thai player Udomchoke. He gained over 200 ranking spots and two Challenger titles this year.
Tomas won his first tournament title of the ATP Series in Palermo, Italy in 2004. In the same year he got into the world's top 50. He also represented our country at the Olympic Games in Athens where he was defeated in the quarterfinal by the American Dent. However, before that he defeated german player Mayer and the world number one Roger Federer (Tomas was the last player who had managed to defeat him that year) and Spaniard Robredo. Two weeks later he reached the fourth round at the US Open.
In 2005 he broke through into the third round at Wimbledon and also added his first title at the ATP Masters Series in Paris. There he managed to beat five seeded players. That earned him 25th rank of the ATP ranking. At the US Open Tomas reached the third round. He also managed to beat three players from the world's top ten (Spaniard Nadal in Cincinnati, Cori and Ljubicic on the ATP Masters Series in Paris).
Tomas began the next season (2006) in the Australian Adelaide and carried on by the fourth round at the ATP Masters Series in Indian Wells and the third round in Miami. At the US Open he was defeated in the fourth round by James Blake. On Roland Garros and Wimbledon Tomas worked his way up to the fourth round as well. Between these two Grandslams he reached final of the tournament in Halle. On the ATP Masters Series in Toronto he defeated the second seeded player Rafael Nadal in the third round. Then he helped the Czech Republic's comeback into the Davis Cup world group by two victories against the Netherlands. At the ATP Masters Series in Madrid Tomas successfuly eliminated two players of the world's top ten - Andy Roddick and Rafael Nadal. In October of the 2006 Tomas appeared in the world's top ten for the first time.
In 2007 top Czech player captured his third ATP title (first on grass) in Halle and advanced to his first Grand Slam quarterfinal at Wimbledon. Tomas reached semifinal at the ATP Masters Series in Monte Carlo and Munich, quarterfinal at the ATP Masters Series in Rome. He won three of four matches at the ATP World Team Championship in Dusseldorf to lead his country to final. Tomas closed season with reaching semifinal in Bangkok and Tokyo, quarterfinal in Basel. He helped his country to win 3-2 in Davis Cup over Switzerland to qualify for 2008 World Group.
The next season (2008) Tomas began with the fourth round at the Australian Open and in April he reached the fourth round at the ATP Masters Series in Miami. In Davis Cup quarterfinal tie versus Russia Tomas sprained his right ankle in the fifth set versus Davydenko. In July he reached final in Bastad, in September semifinal in Bangkok and followed with his first Asian title in Tokyo with defeating Roddick in the semifinal and Del Potro in the final. Tomas finished in top 20 for the third straight year.
In 2009 Tomas helped to lead his country to its first Davis Cup final since 1980. He began the season with fourth round at the Australian Open and in May he captured his fifth career ATP World Tour title in Munich. Tomas ended in fourth round at Wimbledon as well. His best results for the rest of the season were quarterfinal efforts in Washington, Cincinnati, Kuala Lumpur and Tokyo.