NEW DELHI: Former India captain and head coach Anil Kumble - known for his calm and composed demeanour both on and off the field - showed his humorous side during commentary on Day 4 of the second Test against South Africa in Guwahati on Tuesday.

Kumble was visibly disappointed with the way opener KL Rahul threw away his wicket with a loose shot. Unable to hide his reaction, he even mimicked Rahul's stroke while analysing the dismissal during the commentary.

The moment, caught live on the broadcast, was quickly clipped and shared across social media, sparking instant buzz among fans.

South Africa spinner Simon Harmer tossed one up outside off, and Rahul leaned forward attempting to flick it across the line. He was beaten on the inside edge, and the ball went on to hit the top of off stump.

India fumbled in the chase of a mammoth 549-run target to end day four at a precarious 27 for 2. Trailing 0-1 in the two-match series, India lost Jaiswal (13) to pacer Marco Jansen in the seventh over and KL Rahul (6) to spinner Simon Harmer in the 10th over.

Kumble, while dissecting the dismissal on Cricket Live, offered a blunt critique of both the delivery and Rahul's shot selection.

"It was a wonderful off-spinner's delivery from Simon Harmer. But KL committed to the shot far too early without reaching the pitch," he said. "The amount of revolutions Harmer put on it gave him that dip, and because KL didn't negate it with his feet, he was always in danger."

"On a fourth or fifth-day pitch with rough outside off, you usually cover all three stumps because an LBW is unlikely from there. KL did take centre, but his off-stump still stayed exposed," he added.

"If you stand on middle-and-off, you can smother or defend most deliveries in that area. But when you're on middle-and-leg, you're forced to reach-your off-stump is vulnerable, and that's exactly what happened."

"He probably thought it was a drivable length, but the dip deceived him. Credit to Harmer, but KL played a shot that wasn't on," Kumble concluded.