[5] He assimilated into Al Sadd's first team at the age of 17 in March 2005, under head coach Doru Isac[6] scoring against Al-Shamal.

He scored 5 goals in Al Sadd's start to the league campaign[8] and then was a crucial member of the Asian Games gold medal-winning Qatar team.

However, in an Olympic qualifying match against Bahrain in February 2007, he got himself injured and was laid-off for more than one year, missing most of Al Sadd's season.

[citation needed] He wasn't able to play in the 2007–08 league season due to injury as Al-Gharafa overtook Al-Sadd for the title.

[9][10] Al Sadd's Asian triumph took them to Japan for the Club World Cup where Khalfan featured and scored against the African champions Esperance in their first match.

[11] During this time, Khalfan accumulated 2 red cards in a row within 2 games in the Qatar Stars League, both in the 89th minute for physical altercations with other players.

[14] Khalfan Ibrahim had a solid start to the season, playing a critical role of an attacking trio (with Mamadou Niang and Raúl González).

After the first 4 games of QSL, Khalfan (with Niang and Raúl) shared the second place on the top scorer table with 3 goals each.

Süper Lig club Beşiktaş were rumored to be interested in signing Khalfan in the off season to replace Hugo Almeida.

He was part of the Qatar squad which played at the FIFA Under-17 World Cup in Peru, scoring one goal in the match against the mighty Netherlands.

Their first major triumph was the Asian Games title won in front of home fans, with Khalfan scoring 2 goals.

[23] He then took part in his first Arabian Gulf Cup, where Qatar couldn't defend their title despite Khalfan scoring one goal against Bahrain.

[24] Khalfan also got a brace in the home match against Indonesia in a 4–0 win, thus officially eliminating them from qualifying, and in the process, making him the top scorer for Qatar in the 2014 WCQ.