"He is on track to play next week," he said. "All going well in the next few days we are hopeful that he will get a start in the next game."
If Guptill cannot play against Worcestershire, his selection for the first test will be based on his good form for Derbyshire, which included his first double-century at first-class level, and the belief his one-day form is transferable to tests.
Guptill's class and shotmaking has never been in question, but his ability to think his way around test attacks has.
In a spluttering 31-test career, the 28-year-old has shown a fondness for the weak attacks of Zimbabwe, Bangladesh and the West Indies, with a frailty against the rest.
Guptill has sought Martin Crowe's help to fix some problems, particularly his footwork on defence, and the public came to appreciate the results at the World Cup, where his unbeaten 237 in the quarter-final against the West Indies was the high-water mark.
He took that form with him to Derby, scoring 290 runs in four innings at 96.6. James Anderson and Stuart Broad at a lively Lord's will present a far greater challenge than a Gloucestershire attack which had Kieran Noema-Barnett bowling first change at Bristol.
Even if Guptill is not available for the final warm-up, you have to wonder how much weight can be put on the hit-out.
The Worcestershire match has been robbed of meaning by having first-class status removed to allow New Zealand to play more than 11.
A tour to England used to be something for players to treasure. Now it is something to squeeze in between the IPL and the Ashes, with once-valued matches against the counties reduced to joke status.
-Kevin Pietersen was told by new England chief Andrew Strauss he will not play for his country again just hours after blasting a career-best 326 not out.
Exiled batsman Pietersen surpassed his previous first-class best of 254 in a mammoth innings for Surrey on day two of their County Championship Division Two match against Leicestershire at The Oval.
South Africa-born Pietersen, who had hoped for an England recall since being axed in the aftermath of their 2013-14 Ashes defeat in Australia, revealed after the day's play he was due to meet Strauss, the ECB's director of cricket, and chief executive Tom Harrison to discuss his international prospects. NZME/AFP