But he is seen as a key member of the squad and Royals are playing in the qualifier on Tuesday (May 24), where they will be hoping to stay on course for Sunday's final.
The winner of the match between Royals and Gujarat Titans goes straight into the final at Ahmedabad (May 29), while the losing side gets another opportunity in a second qualifying match which will take place on Friday (May 27).
That schedule looks set to rule Neesham out of the Steelbacks'opening three matches of their North Group campaign, and his place in the squad will be taken by Kelly, who has been part of the County Championship squad for the past six weeks.
Steelbacks travel to Birmingham Bears on Thursday, host Durham and Friday and then go to Trent Bridge to play Notts Outlaws on Sunday.
They then host Leicestershire Foxes at the County Ground next Wednesday, when they will hope to have Neesham available for selection.
Kelly is a more than handy replacement for the Kiwi international.
The 27-year-old pace bowler has been a regular performer for Perth Scorchers in the Big Bash League, claiming 41 wickets in 27 matches at an average of 19 and with a strike-rate of a wicket every 14 balls.
His most recent Big Bash League performance in mid-January saw him claim four for 25 as Scorchers beat Melbourne Stars by 47 runs.
“This was always in the pipeline with the IPL being as long as it is and obviously they (the Royals) have gone pretty well,” said Steelbacks skipper Josh Cobb.
“I think it’ll be two games Neesham misses and we know plenty about Matt already, there’s not much discrepancy between the two.
"It’s not quite like for like but he gives us four good overs and can hit a long ball too.”