Perhaps he figured that by keeping him away from the crease, it might fire up the young man from Ragama, a small town about 50km north-east of Colombo.
Whatever, the lean, whippy 23-year-old had the best day of his short test career yesterday, and had five for 47 at stumps.
"I'm very happy," he said last night. With good reason. Until he marked out his run-up, things had been progressing smoothly for New Zealand. All seemed set for an afternoon of runmaking in fine conditions on a pitch not offering particular alarms.
Instead, Chameera turned the contest on its ear in the space of 13 deliveries. And the key to his success was pace. Where Mathews had been trundling in at about 125km/h, Chameera was immediately up to 145km/h. Pace matters. Shots get hurried, edges fly hard, the pulse quickens.
Once he had Latham caught at leg gully, Chameera's tail was up. Kane Williamson and Ross Taylor followed in quick order, with pace a contributing factor in both cases.
Later in the day, he removed Tim Southee and Neil Wagner but that first burst of 7-3-17-3 did the damage.
His favourite wicket? "Kane Williamson, because he is the best batsman for New Zealand."
Either side of tea, Mathews was at it again, leaving Chameera wandering about in the outfield for another 35 overs. It made little sense.
Chameera admitted he needed a break after his rousing spell after lunch. He said he's only been bowling quickly for the last couple of years. He knows he has more clicks in him.
"I want to train hard, get some muscles and then I think I can bowl 150km/h one day," he said.
He has the fast-twitch muscles of the speedsters and bundles of enthusiasm. He might not be up with Mitchell Starc or Dale Steyn yet, but he is getting up towards the serious numbers.
He's got a pile of learning to do and will still have some rough days but Sri Lanka look to have uncovered a diamond. The trick now is to work out how best to use his talents.
