United ended the pre-season campaign with a 3-1 defeat against Stade de Reims in France.
The Blades had the lead through Callum Robinson's fourth goal of pre-season but goals from Remi Oudin, Alaixys Romao and Xavier Chavalerin won the contest for the Ligue 1 side.
New club record signing Oli McBurnie was among the substitutes as United played the final game before Saturday's big Premier League kick off at Bournemouth.
The Blades took the lead with the first chance of the game on 10 minutes. The Reims defence remained static in the hope of seeing a flag, but Enda Stevens beat the offside trap to cross from the by-line and ROBINSON expertly volleyed into the top right corner from eight yards out.
Chris Basham saw yellow for a strong challenge, and shortly after Dean Henderson was called into serious action for the first time after tipping over Oudin's effort from the angle.
On 28 minutes the hosts were level. After receiving a short free-kick, Oudin arrowed in a low drive which brought about a sharp save by Henderson, but Alaixys Romao was on hand to fire home the loose ball.
McBurnie made his first appearance for the Blades when he replaced David McGoldrick at half time, whilst Ben Osborn was also introduced in place of Kean Bryan.
The home side took the lead with the first chance of the second half on 49 minutes. A ball over the top of the United defence was seized upon by Oudin who ran clear to stroke the ball beyond Henderson and into the bottom corner.
The Blades responded and Robinson's low cross forced the Riems backline into some evasive action as Osborn looked to attack the back post.
After Boulaye Dia struck the outside of the post in the hunt for a third, the home side did find the net soon after on 55 minutes. Xavier Chavalerin's cross/shot arrowed into the top corner leaving Henderson with no chance.
The Blades missed a good opportunity to reduce the deficit straight away as Robinson headed over Basham's right-wing cross.
United enjoyed greater possession in the final 20 minutes and were denied a second eight minutes from time. Good work by sub Ravel Morrison saw him slip a pass inside the area for McBurnie who saw his low cut-back roll all the way through to fellow sub Kieron Freeman, but his low drive was blocked on the line.
Inside the final five minutes Morrison was unlucky to see a low free-kick graze the outside of the 'keeper's right-hand post.
Stade de Reims: Rajkovic, Romao, Abdelhamid, Disasi, Chavalerin, Dia, Kamara, Oudin, Dingome, Doumbia, Foket. Subs: Konan, Suk, Sissoko, Mbemba, Lemaitre, Mbuku, Costa.
Blades: Henderson, Baldock (K. Freeman 76), Stevens (Jagielka 76), Fleck, Basham, Lundstram (L. Freeman 65), Robinson (Sharp 65), Egan, Norwood (Morrison 76), McGoldrick (McBurnie HT), Bryan (Osborn HT). Unused: Moore, Stearman.