The visitors scored after only four minutes when keeper Fabien Barthez could only parry Paul Thirlwell's free-kick from the right.
After the ball landed to Gavin McCann on the edge of the box, his attempted shot was deflected goalwards off Roy Keane and then looped off Juan Sebastian Veron's head beyond Rio Ferdinand on the goal-line.
Sunderland's goal signalled a United onslaught that started with Paul Scholes unluckily watching his shot hit both posts before being hacked clear.
Macho continued where he left off at the start of the second half with Solskjaer and Veron both denied by his brilliance.
But, as so many teams have found to their cost, United never give in and that proved to be the case again when the home side drew level thanks to the inspirational David Beckham nine minutes from time.
Ferdinand's hopeful punt form midway inside his own half saw four United players spring clear of Sunderland's offside trap.
Beckham was the one to collect the ball to the right of the box and, as Macho raced off his line, the England captain stabbed the ball right-footed past him and into the corner of the net from 12 yards.
Macho then foiled Forlan soon after but the home side sent the massive Old Trafford following home happy by scoring a deserved winner a minute into injury-time.
Wes Brown's cross from the right was met by Forlan ten yards out.
The ball flashed across the box to Mikael Silvestre on the left of the area and his cross back into the centre was headed home by Scholes, who leapt above Macho to score from four yards.