Early career

Khalfan started out with Al-Arabi (his father's club) and was signed by Al-Sadd in 2004.^[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.^[7]

2005–06

2005–06 was a significantly improved season for him when he scored goals in the Qatar League, Crown Prince Cup and Asian Champions League.^{[citation needed]}

2006–07

His performance in 2006–07 played a part in achieving the Asian Player of The Year title. 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]}

2007–08

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

2008–09

He returned from injury in the revamped 2008–09 season. He scored 8 goals in Al-Sadd's first 6 games.^{[citation needed]}

2010–11

Khalfan won the 2011 AFC Champions League with Al Sadd. Khalfan delivered an inspired performance against Suwon in the semi-final second leg to keep the club's hopes alive. He featured in the final against Jeonbuk which was won 4–2 on penalties. He assisted Keita by providing an accurate cross which Keita volleyed into the net, as well as forcing a Jeonbuk defender to head the ball into his own net on the earlier goal. The Koreans scored a late equalizer to make it 2–2, causing the game to go to extra-time and eventually penalties. His performance in the AFC Champions League earned him offers from other clubs, including a contract from Saudi club Al Nassr, however it was announced by the Al Sadd management that they would only take offers from the club in the summer transfer window, as they needed Khalfan to play in the 2011 FIFA Club World Cup.^[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. Abdul Kader Keita's shot from a tight angle was only parried to the far post by Moez Ben Cherifia. Khalfan then reacted the fastest to nod home on the goal-line. The match, which proved to be an ill-tempered affair, was won 2–1. It was capped off with Esperance fans throwing projectiles onto the field and attempting to get past the security barricade.^[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. Al Sadd lost both of the matches in which he was red carded. However, he did not receive any red cards in international competitions.

2011–12

Khalfan finished the 2011–12 Qatar Stars League season as the top league scorer for Al Sadd, with 7 goals.^[12]

He scored a goal in the 2012 Qatar Crown Prince Cup in a 4–2 win over Lekhwiya before getting involved in an altercation with Lekhwiya midfielder Nam Tae-Hee after the match for unsportsmanlike behavior.^[13] He went on to score Al Sadd's only goal against Al Rayyan in the final, being named Man of the Match.^[14]

2012–13

Khalfan Ibrahim had a solid start to the season, playing a critical role of an attacking trio (with Mamadou Niang and Raúl González). They led Al Sadd from a win to another in their first league games, trying to get the club back as Al Sadd had only won 2 domestic competitions and the ACL in the last 5 years after the 2006–07 season in which they won all domestic competitions.

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. Khalfan scored his first hat-trick this season on Al Sailiya game on 22 October, where his team won 4–1 and he was assisted twice by Niang and once by Raúl, recording the second hat-trick scored in the league this season.

On 26 April 2013, in a Crown Prince Cup match against Al Rayyan, he scored an impressive solo goal as he dribbled 60 meters past the entire opposition defense to score a long-range goal. Some news agencies considered it a 'carbon copy' of Diego Maradona's goal against England in the 1986 World Cup,^[15] and also reminiscent of Lionel Messi's 'Maradona goal' in 2007.^[16] It was touted as a contender for the best goal of 2013^[17] and has been described as arguably the best goal by all Qatari players in history.^[18] His teammate, Raúl, stated he was the best player of the season, comparing him to Diego Maradona.^[19]

On 19 May, he was named as the QFA Player of the Year, beating off competition from teammate Raúl Gonzalez.^[20]

2013–14

Khalfan scored his first goal of the 2013–14 season against Al-Ahli on 20 September.

Süper Lig club Beşiktaş were rumored to be interested in signing Khalfan in the off season to replace Hugo Almeida.^[21]

2014–15

On 22 September 2014, he scored his 63rd goal for Al Sadd against Al Shahania in a 3–2 win, surpassing Carlos Tenorio's 5-year-old record of 62 goals to become Al Sadd's all-time scorer.^[22]