Forlan, standing unmarked at the near post six yards out, rose to head home Michael Silvestre's cross from the left side of the Villa box. There were no inhibitions when it came to celebrating the equaliser as Forlan whipped off his shirt and raced to the touchline were he was engulfed by his team-mates.
Yet, but for the exuberance of the Forlan goal, there was little to cheer in this lethargic United showing.
The last 15 minutes apart, there was little to suggest an improvement in United's form.
Aston Villa had not scored away in the Premiership before this game, with four league defeats out of four.
They should have broken the deadlock in the 21st minute when Dion Dublin's clever flick over the top of the United defence found Stefan Moore free in the penalty area.
As the defence stood and stared, Moore fired in a shot which was superbly saved by goalkeeper Fabien Barthez with his feet.
United failed to heed the warning and Villa went ahead 13 minutes later. Mark Kinsella fired his corner to the far post and Olof Mellberg powered his way past United's defenders to head home from six yards.
The goal stirred United from their slumbers with Beckham rattling the Aston Villa bar with a 20-yard shot.
Apart from that, the goal and a late Ole Gunnar Solskjaer header, which was well saved by Villa keeper Peter Enckelman, there was little for the home fans to cheer.