United got a dream start with a 2-0 lead, but dropped to 2-3 before the equalizer came.
A goal that may have saved Erik ten Hag's job.
With three losses in the first six matches in the Premier League and 13th place in the table, the Dutchman is already heavily criticized.
He could hardly afford a new setback after 0-3 against Tottenham on Sunday.
United made a lightning start and led 2-0 after 20 minutes with goals from Marcus Rashford and Rasmus Højlund.
But the luck was short-lived.
Pepé reduced in the 27th minute and seven minutes later the home team had equalized through Samu.
He became a two-goal scorer five minutes into the second half and the turnaround was complete.
In the hunt for equalization, the next blow came. Bruno Fernandes was sent off for the second match in a row when he received his second yellow card.
But Harry Maguire, who started on the bench, came in and saved a point.
The big club, which has two points after two matches, plays its next match on Sunday away against Aston Villa in the Premier League.