He achieved a career-high singles ranking of World No. 71 in May 2000 and reached one ATP Tour singles final at Tashkent in 1999.
The biggest win of Bastl's tennis career came in the second round of the 2002 Wimbledon Championships, where he caused one of the biggest upsets in Wimbledon and Grand Slam history by defeating seven-time champion Pete Sampras, winning in five sets by the score of 6–3, 6–2, 4–6, 3–6, 6–4. Bastl had only been in the main draw of 2002 Wimbledon as a lucky loser, having previously lost to Alexander Waske in three straight sets in the final qualifying round at Roehampton. He subsequently lost in the third round to eventual runner-up David Nalbandian.
He was the first player to be beaten by Andy Murray in the main draw of a Grand Slam tournament, at Wimbledon in 2005, with Murray winning 6–4, 6–2, 6–2.