Ireland coach Phil Simmons admitted to a few nerves as his side scraped home against Zimbabwe but praised his players' 'hearts of steel' in securing their crucial World Cup Group B win.

Ireland beat the Africans by five runs in a tense finish in Tasmania after allowing their opponents back into the game late on.

"They keep doing this but if it happens all the time and when you win it tends to be nice," said Simmons.

"They've done it again where we've gone to the last over and we've shown that we have hearts of steel and strength of mind right through. It's good to see."

Zimbabwe were Ireland's second Test nation scalp after victory in the opening game against the West Indies, but it now looks like they will need a third against either India or Pakisatan to make the quarter-finals.

Despite the apparent scale of that task, Simmons is bullish about his team's chances.

"We came here to win all six," he said. "We've won three and lost one so we've just got to work on how to win the two."

The Trinidadian was also full of praise for the batting partnership of Ed Joyce (112) and Andrew Balbirnie (97), which powered Ireland to their best ever World Cup total of 331 for eight.

"Balbirnie deserved a hundred for the way he batted," said Simmons. He complimented Ed in the way he batted and Ed showed his class today. I hope he continues going for the rest of the tournament."

Joyce also hailed the impact of Balbirnie (24) in his first World Cup.

"He's come into the team and done brilliantly," said Joyce. "He took the pressure off me today. He hit his first ball for four and rotated the strike really well."

Captain William Porterfield was impressed with bowler Alex Cusack, who took four for 32.

"To end up four for 30 off his just under 10 was a fantastic effort," said Porterfield. "He never seems to let us down and today was no different."

Porterfield also defended the bowling of all-rounder Kevin O'Brien, who got smashed for 19 in the penultimate over to open the door for Zimbabwe before Cusack close out the win.

"He bowls at difficult times. You look at his overs and he never shies away from that responsibility," said Porterfield.

"He's bowled very well at stages and been unlucky. It's not an easy over to bowl. On another day he wins the game in the second-last over.

"He got hold of a couple today and with four men out it's a difficult job."

Porterfield said he wasn't sure whether John Mooney had touched the boundary when catching Sean Williams - in a controversial dismissal upheld by the third umpire - but praised the Dubliner for his fantastic technique.

"I thought it was a fantastic catch. It's a great skill, he's under pressure," said the Donemana man.

"He's close to the line. I saw a couple of replays on the big screen but that was pretty inconclusive. It's very difficult to tell when you're a fielder on the rope but the way he took the catch was a great skill."