[3][4][5] Born in the Uzbek SSR in the Soviet Union (now Uzbekistan), he emigrated to Turkey with his mother in 2004 and he started to play for the Taçspor Tennis Club of İstanbul.

At the 2009 US Open, İlhan qualified for the main draw of a Grand Slam for the first time in his career.

He defeated his first-round opponent Benjamin Becker, but then lost to Jürgen Melzer.

However, due to Gilles Simon's injury a spot opened up for an additional player to appear on the main draw.

Marsel İlhan proved that he was a worthy "Lucky loser" as he easily defeated former World No.

In the first round of Wimbledon 2010 he defeated Brazilian Marcos Daniel 3–2, where he made a superb comeback from 0–2 and eventually won the match.

On 20 September 2010 he won his second ATP Challenger Tournament, in Banja Luka, Bosnia and Herzegovina on clay by beating Pere Riba in the final 2–0, 6–0, 7–6.

Therefore, he played directly in the main draw 2011 Australian Open for the first time during a Grand Slam tournament in his professional career.

In the 2011 Indian Wells Masters, he lost against Milos Raonic from Canada in straight sets 6–2 and 7–6.