Wellington: New Zealand coach John Wright has asked his players to go ahead to be at their aggressive best against Sri Lanka in the first semifinal of the cricket World Cup in Colombo on Tuesday.

New Zealand skipper Daniel Vettori and substitute player Kyle Mills were fined 90 and 120 per cent of their match fees after involving in an altercation with Faf du Plessis during the quarterfinal against South Africa.

However, coach Wright did not read too much into the incident and said aggression is important for success and allowed the team to go full throttle against Lankans at Colombo.

"I like the aggression of the team, particularly in the field. That`s important. We`ve got to play with passion and they`re showing that. The odd thing happens ... but that`s international sport," Wright told New Zealand media from Colombo.

The incident had happened in the 28th over when Vettori and Mills, who had brought drinks to the ground, were deemed to have verbally harassed du Plessis after AB de Villiers` runout.

Mills, who interestingly pleaded not guilty to his antics, headed home after being ruled out of the rest of the tournament because of a muscle injury and was replaced by Andy McKay.

"It made reasonably interesting viewing for those out there. It happened and it was dealt with. The players on both sides knew there was a lot at stake, which is what you expect of any South Africa/New Zealand contest," Wright said.

"I think the boys were committed, they wanted to win and made their presence felt. We`re all pretty pleased right now. We did a lot of preparation for that game and achieved plenty of game-plan targets."

The former India coach, who turned the hapless Kiwis into potential match-winners after taking over the job barely a month before the team left for the sub-continent, feels the team needs to bat well against Sri Lanka especially after falling 20 runs short against South Africa.

"We were probably 20 runs short (against South Africa), but knew if [we] got 220-plus it was defendable. We`re making up for it in the field and with the ball."

"We have to bat well (against Sri Lanka), that`s the key for us," he said.

"I think the boys are learning -- you need those wickets in hand going into the last overs and you set those targets.”

"We`ll look inwards and focus very much on trying to get better as a unit," he said.

The Black Caps, who are playing in their sixth World Cup semifinal in 10 tournaments, have won many ICC fairplay and ICC spirit awards.