Mumbai Indians (MI) are at the centre of a huge storm in the Indian Premier League (IPL) 2026, after being accused of misusing the concussion substitute rule to replace injured all-rounder Mitchell Santner in the middle of Thursday's match against the Chennai Super Kings (CSK). The New Zealander hurt his shoulder while taking a catch of CSK batter Kartik Sharma off the bowling of Jasprit Bumrah. The spin-bowling all-rounder got up clutching his shoulder and had to be taken off. Soon, MI made a formal request to replace him with Shardul Thakur, and it was accepted.

The substitution triggered a massive controversy, with questions being raised not just over the alleged misuse of the concussion substitute rule but also whether Shardul could be considered a like-for-like replacement for Santner. Under IPL playing conditions, a concussion substitute is only allowed if a player has suffered a head or neck injury. The extent of the injury must be verified with a medical diagnosis before being approved by the match referee.

In Santner's case, the injury appeared to be to his shoulder, while the substitute request was made on the basis of neurological symptoms. He was even spotted icing his shoulder while sitting in the Mumbai Indians dressing room later in the match.

Mahela Jayawardene, the MI coach, couldn't escape questions on the concussion substitution controversy in the press conference as social media erupted over the misuse of the rule. He said that both Santner's neck and shoulder were hurt while taking the catch. He also revealed that when the management asked for a concussion substitute, the match referee allowed Shardul to take his place.

"He hit his head first and neck. Obviously, the shoulder as well," Jayawardene said. "He went for a scan. Once he got back, he felt dizziness. So, he was lying down. Yes, the ice was there for the shoulder, but he felt he wasn't stable. So, we took him for a scan."

"We requested (for a concussion substitute). Obviously, it is the match referee and the umpires' discretion. They allowed Shardul," he said. "Mitch will be disappointed that his batting prowess was matched to Shardul, but it is what it is. Hopefully, it's not too bad."

Even Shardul's arrival could not change MI's fortunes, with the franchise suffering a damning 103-run defeat.