In June 2009, Tahri improved his 2000 m outdoor steeplechase European record with a run of 5:15.36 in Nancy, France.

He set a new 3000 m outdoor steeplechase European record of 8:01.18 in finishing third in the final of the 2009 World Championships in Berlin.

[1] On 25 June 2010, Tahri set a new world-record time of 5:13.47 in the 2000m outdoor steeplechase race in Tomblaine, France.

But Tahri's 2000m outdoor steeplechase world record was broken only 5 days later by his compatriot Mahiedine Mekhissi-Benabbad.

[2] On 29 June 2010, Tahri won the 3000m outdoor steeplechase race in Metz in the world's fastest time (8:03.72) of the year.