Andrea Lovotti showed "crass stupidity" when he was sent off for a tip-tackle in Italy's defeat by South Africa at the World Cup, says coach Conor O'Shea.

Lovetti was dismissed in the 42nd minute for his part in picking up the Springboks' Duane Vermeulen and dropping him headfirst to the floor.

Italy were trailing 17-3 but were close to their opponents' line before the red, but went on to lose 49-3.

"I'm destroyed for everybody because we worked so hard," O'Shea said.

"At 17-3, we had to hang in and do something and we get to the start of the second half, we're close to the line and then just crass stupidity.

"We are hurting massively because we came here to show our best and we didn't get that opportunity in the second half.

"I thought the boys fought valiantly but when you're down in numbers against a great side, it's just impossible."

A win would have seen Italy progress to the knockout stage but defeat leaves them likely needing to beat two-time defending champions New Zealand in their final pool game to go through.

Lovotti's dismissal came when both he and team-mate Nicola Quaglio lifted number eight Vermeulen at a ruck, and O'Shea said both of his players could have been sent off.

"It was just a stupid act," he added.

"You plan for a lot of things in rugby, but you can't plan for that. Andrea is more destroyed than us, but we are all destroyed."

Erasmus plays down Kolbe injury

Winger Cheslin Kolbe impressed again for South Africa, scoring two of the Springboks' seven tries.

"He played a wonderful game on attack and defence," South Africa coach Rassie Erasmus said.

"He must be one of the best players in the world, along with [New Zealand's] Sevu Reece and Damian McKenzie that have that X-factor to create something from nothing."

Kolbe limped off late in the second half after twisting his ankle in a tackle but Erasmus played down injury fears.

"His ankle is fine, he did roll it a bit and with a minute left, even having used all our substitutes, we thought it was best to get him off the field," he said.