By Mark Geenty of NZPA

Wellington, March 13 NZPA - New Zealand cricket wicketkeeper Brendon McCullum will eventually give up the gloves to focus on batting -- it's just a matter of when.

Coach Mark Greatbatch confirmed McCullum would keep wicket in the two-test series against Australia starting at the Basin Reserve next Friday despite handing up the gloves after the first one-day international in Napier.

He was battling a sore back, and the physical rigours of opening the batting and taking the gloves in five ODIs packed into 10 days saw Gareth Hopkins take over behind the stumps. But that could become a more permanent arrangement.

"He's going to have to make a decision at some stage. He's going to be keeping in the test matches but, for himself, he'll need to make a decision," Greatbatch said.

McCullum sowed the seeds in a television interview this week when he revealed he would eventually like to be a batsman only, and it clearly has been discussed with Greatbatch and captain Daniel Vettori.

It would place more heat on McCullum in the test side to bat in the top-six for the balance of the team, although McCullum has tasted success higher up in the test order, even at the lofty perch of No 3.

The 28-year-old averages 34.33 from 50 tests; 29.24 from 170 ODIs and 36.55 from 33 Twenty20 internationals at a strike rate of 133.

In the Twenty20 and ODI series against Australia his form has been excellent, with his unforgettable 116 not out in Christchurch then scores of 45, 24, 23 and 61 in the ODI series which concludes today with the fifth match at Westpac Stadium.

He looked set for a third ODI century at Eden Park on Thursday after cruising to 50 off 53 balls, but his innings stalled a touch before he chipped a catch to short mid-wicket.

"He's dynamic, the modern game it's the place to bat. There's not any more pressure on him. I thought his performance was solid. He's got in every time and he just hasn't converted two of those four," Greatbatch said.

Despite his batting heroics, McCullum highlighted some of the problems in the ODI batting lineup which collapsed badly in Hamilton and Auckland as Australia sealed the series 3-1.

Ross Taylor (twice) and Daniel Vettori were the only New Zealand half-centurymakers to date, with no one passing 70 as the hosts desperately needed a batting anchor.

Greatbatch observed in Hamilton there were six New Zealand scores over 20 but only Taylor (62) got past the half-century.

"Hopefully we're going to be more consistent. We've got 22 ODIs before the next World Cup. We've got to start getting a method and key people in positions that can do the job for us."

Most of those ODIs in the coming year will be on the subcontinent, with scheduled tours to Sri Lanka, Bangladesh and India, with the World Cup set down for the subcontinent next February. Plenty of time to hone a coherent batting strategy, Greatbatch hoped.

"We've got to be more ruthless. Our top order are good players, dynamic players, but when they're dominating they want to finish the game. (Ricky) Ponting took his luck and got 50 off 35. (Michael) Hussey does it consistently, he makes it happen."