The injury came as the highly-rated Irish defender stretched into a tackle at the end of a burst forward. He was immediately replaced by Stephen Carr.
Our new Head Coach suggested at his post-match press conference that Kelly suffered an ankle injury and that Goran Bunjevcevic also had to be withdrawn with a knock at half-time.
Kelly joins young strikers Lee Barnard (broken collar bone) and Jamie Slabber (shoulder) as pre-season casualties while Michael Brown (knee) also picked up a knock in Sweden.
The positive news saw Robbie Keane grab a second goal in pre-season and Jamie Redknapp complete his first friendly action of the summer as the home side battled back from a goal down to take the spoils.
We produced our best football so far in pre-season in the first half highlighted by Keane's excellent opening goal after 20 minutes.
Skipper Redknapp, looking sharp for his first game, spread play to Johnnie Jackson, he laid the ball back to Sean Davis who dinked it over the defensive line for Keane to lash home from 12 yards.
However, the lead only lasted a minute - United hit a long ball forward that found it's way to Jon Harley who crashed a left-foot shot into the top corner from 20 yards.
Blades went close a couple of times at the end of the first half and had the better of the second half against what was a much younger line-up, even more so on Redknapp's departure after 57 minutes.
Kasey Keller saved bravely from Barry Hayles but was left stranded when Paddy Kenny's clearance upfield stood up on landing and allowed substitute Jonathan Forte to lob home from the edge of the box.
MINUTE BY MINUTE GUIDE
10mins: First serious attack of game, two crosses flashed across goal, ball eventually came out to Liddell but Mabizela blocked superbly.
13mins: Liddell half-volley from 30 yards, decent strike but always rising.
15mins: Keane curler from 20 yards no problems for Kenny.
19mins: GOAL. Lovely goal. Redknapp to Jackson, back to Davis, dinked into Keane, clinical finish with left foot from 12 yards. 1-0.
20mins: GOAL. Blades hit back immediately with Harley's 20-yard screamer into top corner. 1-1.
25mins: Backheels from Liddell and Hayles set up Tonge who couldn't keep decent shooting chance on target.
26mins: Harley dribbler straight at Keller from 22 yards.
34mins: Keller out quickly to save at Hayles' feet.
37mins: CLOSE. Tongue header from Wright's free-kick landed on roof of net.
45mins: Hayles sliding in just inches away from Harley's cross.
Half-time: Sheffield United 1, Spurs 1
48mins: Yeates cut in from right, low left foot shot straight at Kenny.
52mins: SAVE. Keller out bravely amongst the studs as Hayles slid in for loose ball.
67mins: GOAL. Kenny clearance over the top, ball stood up on landing allowing Forte to lob stranded Keller. 1-2.
75mins: SAVE. Keller did well to hang on to Tongue's wicked in-swinging free-kick from left flank with Ward ready to pounce.
80mins: INJURY. Kelly stretchered off after challenge with Francis, over-stretching to try and make ball after a long dribble. Replaced by Carr.
Line-ups: 4-4-2: Sheffield United: Kenny, Francis, Wright (Quinn, 45), Jagielka, Morgan, Thirlwell (Sharp, 80), Liddell (Forte, 61), Tonge (Ross, 80), Gray (Montgomery, 61), Hayles (Ward, 61), Harley. Subs: Barnes, Bromby, Ndlovu.
Spurs: 4-5-1: Keller, Kelly (Carr, 80), King (Gardner, 45), Richards, Bunjevcevic (McKie, 45), Mabizela, Redknapp (Hughes, 57), Davis, Jackson (Ricketts, 67), Yeates, Keane (Malcolm, 45). Subs: Fulop, Mendes, Doherty, Defoe.
Jacques Santini's pre-season injury woes continued as Stephen Kelly was stretchered off in Sunday's defeat at Bramall Lane.