Johnson broke the thumb of Prasanna Jayawardene and the forefinger of Sangakkara, who will play no further part in the series.
Melbourne: Sri Lanka's bruised batsmen might care to disagree, but Mitchell Johnson cares about the well-being of his victims off the pitch, according to Australia captain Michael Clarke.
The mercurial paceman was justly named man-of-the-match on Friday for his wrecking ball performance in Australia's innings and 201-run victory at the Melbourne Cricket Ground that gave the hosts an unassailable 2-0 lead in the three-match series.
Johnson scored an unbeaten 92 and took six wickets, but his venomous short-pitched bowling left its mark on Sri Lanka, breaking the thumb of wicketkeeper Prasanna Jayawardene and the forefinger of Kumar Sangakkara, who will play no further part in the series.
"I think the other side that a lot of people don't get to see of Mitch is that on the field, he is as aggressive as anybody, but he's the first guy today to walk into the change-room and make sure everything's okay with Sangakkara," Clarke said.
"I think a lot of people don't get to see that side. He will fight hard, there's no doubt about it, and wants to have success for Australia and help us win, but off the field he's the first guy to go and make sure in this instance Kumar's OK."
Johnson's outstanding return, having been dumped for the first Test victory in Hobart, leaves Clarke and his fellow selectors with a dilemma ahead of the dead rubber Test in Sydney starting on January 3.
Clarke said paceman Mitchell Starc, who was controversially rested for the MCG Test despite being fit and in-form, would bowl in Sydney, meaning a battle for the remaining pace bowling places on a wicket traditionally conducive to spin.
"If Mitchell Johnson performed the way he did in this Test match, it's going to be very hard to leave him out," Clarke said.
Johnson missed a year of cricket through injury and watched as Australia's pace attack of Ben Hilfenhaus, Peter Siddle and James Pattinson routed India during their tour the previous summer. The left-armer said he had never lost faith while out in the international wilderness and put his hand up to become an all-rounder, with Shane Watson set to miss the Sydney Test with a calf strain.
"I think I can become an all-rounder, I've always enjoyed my batting, it's just being consistent with it," the 31-year-old said.
"If I can take what I did out there today and yesterday into the future and be consistent with it, I think I could become a good all-rounder. Time will tell."
With pace spearhead Siddle likely to be retained, Jackson Bird appears set to miss out on the final Test in Sydney despite an impressive four wickets on debut. Clarke paid tribute to the 26-year-old, who slotted into the team like a seasoned veteran and removed Sri Lanka captain Mahela Jayawardene for a duck and middle-order batsman Thilan Samaraweera for one in quick succession in the second innings to hasten Sri Lanka's demise.
"His control with the new ball is an area I think we've been looking for," Clarke said.
"I think he filled that role of [injured] Ben Hilfenhaus. Be able to swing the new ball away from the right-hander and then take it across the left-hander off the wicket is a great strength.
"Bird played a huge part in Mitch's success in the first innings to be able to build pressure and it allows a bowler like Mitch to attack."