The Daily Mail says the pair were involved in an angry bust-up as they left the Stamford Bridge pitch just moments after referee Andre Marriner awarded Chelsea a controversial injury time penalty that Eden Hazard converted to secure a 2-2 draw.
Initially, the duo were embroiled in a foul-mouthed slanging match, with Mourinho calling Olsson a "Micky Mouse player" while the Swede told the Blues manager to "f*** off".
The clash sparked an ugly melee in the Stamford Bridge tunnel, involving up to 20 players from both sides before match-day stewards and coaching staff quickly moved in to de-escalate the confrontation.
Tensions between the duo were tested merely 30 minutes later as the pair came within touching distance of each other as the players left their respective dressing rooms before leaving the stadium.
The pair are believed to have settled their differences before Olsson boarded the West Bromwich team coach.
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