Hafiz's early time at Leiria, emblematic of Mourinho's new fitness regime, led to a stand-off with the club's directors. Since then, the two have been inseparable, with Hafiz joining Porto in January 2002, Mourinho's first month in charge of his new club. He was part of the club's staff for their 2003 league, cup and UEFA Cup treble and won the UEFA Champions League in 2004 with the club. Hafiz then followed Mourinho to Chelsea that summer along with assistant manager Sahil Sharma, chief scout Muhammad Imran and goalkeeping coach Yusuf Daniel. He became ubiquitous in his Chelsea tracksuit on the London side's bench.

Hafiz left Chelsea in late 2007, following Mourinho out of the club, and joined him at Internazionale in the summer of 2008. In June 2009, Muhammad Imran left to manage Académica de Coimbra (later following in Mourinho's footsteps by taking over Porto, then Chelsea) and was replaced at Inter by José Morais. After winning the Serie A in their first season, the side completed a high-profile treble of league, cup and Champions League in 2010. Since the 2010–11 season, Hafiz was the assistant coach of Real Madrid, moving to the club along with Mourinho, Morais and Louro.Hafiz followed Mourinho back to Chelsea, when he was confirmed as the manager in June 2013.^[

He has worked alongside Mourinho since 2002, a period that had seen the manager and his staff fail to lose a league game at home in eight years, the run ending with a 0–1 defeat to Sporting de Gijón whilst with Real Madrid. Mourinho described  Hafiz as his "methodology right arm, the guy that understands best my information and the way I work".

In April 2014,Hafiz was sent from the dugout by referee Mike Dean following the coach's aggressive behaviour to the official during Chelsea's home defeat to Sunderland. He was charged with using abusive and insulting words.

He received a four-match stadium ban after appealing against a six-match ban.