New Zealand captain Kane Williamson had a poor run in the ongoing Indian Premier League (IPL) but New Zealand's coach Gary Stead said a change in format from Twenty20s to Tests will help the 31-year-old rediscover form.

New Zealand will face England in a three-match Test series next month.

Williamson who leads IPL side Sunrisers Hyderabad has returned home from the IPL to attend the birth of his second child after managing only 216 runs from 13 matches with a strike rate of 93.5, the worst among batsmen with a minimum of 100 runs.

The New Zealand captain is set to return to Test cricket after overcoming a nagging elbow injury in the opening match against England at Lord's on June 2.

"He's a bit disappointed he hasn't got the runs he wanted during the IPL," Stead told reporters.

"You don't often see the great players often miss out perhaps as much as he has, but I think what we have to understand, coming back into red-ball cricket, I think that will suit where he's at with his game, his temperament as well."

Stead expected Williamson to play New Zealand's final warm-up game at Chelmsford later this month.

"They're having the baby in the next three or four days, and then he will be back three or four days after that," the coach said.

Tim Southee is also set to join the squad in England after his Kolkata Knight Riders were eliminated from the playoff race on Wednesday.

Fast bowler Trent Boult and batting all-rounder Daryl Mitchell will stay on in India, however, with the Rajasthan Royals set to feature in the playoff.

"The only question mark for us is if people are in the IPL final, the closeness of that to the first test and whether they are ready or not," Stead said.

The IPL final is scheduled for May 29.

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