Cricket: Southee optimistic over Boult's fitness

New Zealand Black Caps bowler Trent Boult and Tim Southee. Photo / Brett Phibbs.

New ball spearhead Tim Southee today expressed cautious optimism Trent Boult will be ready for the deciding third test against Australia this week.

Swing bowler Boult has been limited by an ongoing back issue, which has reduced his effectiveness in the first two tests, despite taking six wickets at Brisbane and Perth.

The world's sixth-ranked bowler, Boult has been troubled by an irritated disc, similar to the injury Southee sustained in the first test, but which healed quickly and enabled him to be New Zealand's best bowler in the second test at the Waca.

''He's in good hands with the physio (Tommy Simsek)," Southee said today.

''We'll know more in the next few days."

Southee acknowledged New Zealand's bowlers have been below par for much of the first two tests, although there were encouraging signs in the latter part of the second test that they were improving.

''I don't think as a bowling group we've hit our straps the way we'd like on this tour so far, but there's still one game to go and hopefully we can show the high standards we've shown for a long time now," Southee said.

''There's a lot of depth in the bowling group and if he is unavailable I'm sure someone will step up and fill his shoes."

For all the imponderables going into test cricket's first day-night test starting on Friday, Southee said one of the points that is expected is more help for the seamers under lights.

''We got a lot out of the two days (against a West Australian XI in Perth last weekend). It's still a learning process to try and figure out.

''We're continuing to learn about what the pink ball is going to throw at us, just the way it reacts at certain times of the day and how you're going to cope with different phases throughout the day."

New Zealand will be back at the practice nets at Adelaide Oval tomorrow and will have two full days to prepare for a test they must win to square the three-match series.