In 2002, Monfils finished as 24th at the Dutch Junior Open. In the same year, he won the German Junior Open (defeating Bayer). Monfils ended the year ranked the 4th junior in the world. He also represented France in the junior Davis Cup.Monfils got off to a positive start in 2003 as earned his first career ATP point at the France Futures No.13 by reaching the second round. He also reached the second round at France #14, Egypt #2, and Spain #28. In that year, he played a total of nine Futures events. This included a showing in the doubles final at Spain #27. In junior events, he was the runner-up at Orange Bowl (losing to Marcos Baghdatis) and USTA International Winter Championships (losing to Sebastian Rieschick). He reached the quarter-final of the Australian Open juniors tournament (losing to Florin Mergea) and won the doubles title at the Victorian Junior Championships (with Josselin Ouanna). He was number 21 in junior rankings at the end of the year.
In 2004, the French teenager finished as the world's number 1 junior, winning three of four junior Grand Slam events (Australian Open, French Open, Wimbledon). He improved his INDESIT ATP Entry Ranking by over 700 positions. In October, he made his ATP debut as a wild card entrant in Metz and reached the quarter-final, defeating Juwana Doit and Olivier Patience and losing to countryman Richard Gasquet. He qualified for the ATP Masters Series in Paris and reached the second round beating former Top 10 player Thomas Enqvist before falling to No. 3 Lleyton Hewitt. He won junior titles at the Australian Open (defeating Ouanna), French Open (defeating Kuznetsov) and Wimbledon (defeating Kasiri).
In his first tournament of 2006, in Doha, he reached the final but lost 3–6, 6–7 to world number 1 Roger Federer. In a surprising event in Las Vegas there was a Tennis paddle tournament held by the Tennis Channel. Monfils was given a wildcard into the doubles event but became more interested and inquired about getting a singles wildcard into the main draw. However, he received an entry into the qualifying singles (which he won), as it would have been unfair for the other players in the main draw. Monfils competed in the main draw of this Paddle tennis Tournament and surprised everyone when he outed world no.1 Paddle Tennis player Scott Freedman and eventually went on to win the whole tournament.Later on in 2006 Monfils reached the semi-finals of the Rome Tennis Masters Series before losing to the eventual champion Rafael Nadal. En route to the semi-finals Monfils defeated former world number one Andy Roddick. He then entered the ATP Hamburg masters event where he lost in straight sets to fellow teenager Andy Murray in the first round. After that he faced Murray once more, this time in the first round of the French Open
His recent knee injury, caused by Osgood-Schlatter disease resulted in his withdrawal from the Rome and the Madrid Masters. He however competed at the Roland Garros, and won his first round match against Bobby Reynolds 6–2, 6–3, 6–1. He then completed another straight sets victory in the second round by overcoming Victor Crivoi 6–4, 6–3, 6–3. In the third round, Monfils beat Jürgen Melzer 6–2, 4–6, 6–3, 6–1. Against Melzer, Monfils made one of the most spectacular plays[says who?] of the tournament, hitting a diving lob back to Melzer, sliding to save another point of Melzer and then putting the point away. He then played a much anticipated fourth round match against Andy Roddick, who made 28 unforced errors and allowing Monfils to win in straight sets 6–4, 6–2, 6–3. Monfils lost, as in the previous year, to Roger Federer, this time in the quarterfinals.Monfils withdrew from the 2009 Wimbledon Championships due to a wrist injury.Monfils returned to competition at the 2009 Montreal Masters. In his first round match he defeated former grand slam champion Marat Safin 6–2, 3–6, 6–2. He lost to qualifier Juan Carlos Ferrero in his second match 6–3, 7–6 ending his Master Series campaign.In the 2009 US Open he lost to world No. 3 Rafael Nadal in the fourth round in four sets.
BEST POINT 2009 - GAEL MONFILS