Just when Manchester United's players were starting to have the look of potential champions, they threw in their sloppiest performance of the season to lose to the Premier League's worst team.

A 2-1 home loss to last-place Sheffield United not only prevented Man United from returning to first place at the expense of fierce rival Manchester City. It also undid much of the impressive work Ole Gunnar Solskjaer's team has produced in recent months, exposing its lack of depth and defensive frailties in an alarming 90 minutes at Old Trafford.

"We're surprised," Solskjaer said after United's first loss in the league since Nov. 1. "We have been the most consistent team the last few months but it just hit us today."

Suddenly, it's advantage Man City in a title race that has ebbed and flowed all season. City, which has won its last seven games, leads by a point from United and has a game in hand over its neighbor around the halfway stage.

A series of defensive blunders led to Sheffield United's deflected 74th-minute winner — scored by Oliver Burke — that also enlivened the battle to avoid relegation.

That's two victories in three league matches for Chris Wilder's team, which was winless until beating Newcastle on Jan. 12 and heading for one of the worst campaigns in the Premier League's 29-year history.

Now, the gap to safety is only 10 points and the so-called "great escape" could be on.

"We have had to play near-perfect from our point of view against world-class players and a team that is flying high," Wilder said. "All season we have had pretty tight games and not come out the right side. We took our big moments."

Thomas Tuchel's first game in charge of Chelsea ended in a 0-0 draw at home to Wolves, while Burnley twice came from behind to beat Aston Villa 3-2.

England goalkeeper Jordan Pickford's error allowed third-place Leicester to equalize in the second half in a 1-1 draw at Everton, while Brighton and Fulham drew 0-0.

SLOPPY UNITED

Man United's players have made a habit of coming from behind to win games in the league — they have done so seven times, all away from home — but they came up short this time against Sheffield United, conceding a winning goal Solskjaer described as "so poor, so sloppy."

Goalkeeper David De Gea passed the ball out straight to visiting midfielder John Lundstram, who passed for Burke to have a shot that was blocked by Axel Tuanzebe. Lundstram collected the loose ball and again fed Burke, who was given time and space to send in a shot that struck the outstretched leg of Tuanzebe and went in off the underside of the crossbar.

That gave Sheffield United the lead for the second time, with Kean Bryan's 23rd-minute header from a corner having been canceled out by Harry Maguire's header, which also came from a corner in the 64th from left back Alex Telles.

Solskjaer rotated his squad by fielding Tuanzebe, United's fourth-choice center back, and Telles while resting central midfielders Fred and Scott McTominay, who have been instrumental to United's unbeaten three-month run in the league. Bruno Fernandes and Paul Pogba regularly misplaced passes in midfield and United missed the presence in attack of Edinson Cavani, who was also benched.

"It's time to stand up and be counted because it's easy when you are winning football matches," Maguire said. "When you lose it is about how quickly you bounce back."

United next plays away to Arsenal on Saturday.

TUCHEL'S DEBUT

A new 3-4-2-1 formation. A funky deployment of some players, including two No. 10s and a forward in Callum Hudson-Odoi at wing back. A possession-based approach that resulted in more passes made (820) than any other team in a single game this season.

Thomas Tuchel certainly put his tactical stamp on Chelsea in his first match in charge of the team. A win proved elusive for the German coach, however.

In a game that highlighted the size of the job facing Tuchel following his arrival Tuesday as Frank Lampard's replacement, Chelsea labored to a 0-0 draw with Wolves that heralded the start of another era at a club where managerial changes are commonplace.

Tuchel, who took charge of just one training session ahead of the game, said he was "very happy with what I saw."

"I liked the attitude and energy," he said, "and I just told the team that I will not allow anybody to doubt from here."

Still, Chelsea is languishing in eighth place, five points off the top four, and has just two wins from its last nine games.

"I'm absolutely sure we have the capacity to hurt everybody in every league and competition," Tuchel said, "and it's my job to bring evidence of that as fast as possible."