On Merseyside, Tottenham avoided extending an unwanted club record by halting their losing run with a late equaliser to earn a crunch 1-1 draw with Liverpool - who were booed off by their supporters.
"I think it's understandable for fans to be frustrated because it has happened so many times that they have seen the home team not picking up the points they are expecting, us conceding goals in the last minute," said head coach Arne Slot.
At Old Trafford, Fernandes provided assists for two United goals on Sunday to take his tally for the season to 16. The record for a single Premier League campaign is 20, with Thierry Henry and Kevin De Bruyne both reaching that mark.
Fernandes, who now has 100 assists as a United player, has up to eight more games to set a new record in England's top division. He also set a new club record for United in a single Premier League season, overtaking David Beckham's 15 in 1999-2000.
Casemiro headed United in front from Fernandes' corner in the 53rd minute. Villa levelled through Ross Barkley, but the Portuguese midfielder was the provider again when Matheus Cunha sidefooted past Emiliano Martinez.
Benjamin Sesko came off the bench to score his eighth goal in 10 games and seal the win.
Victory saw Michael Carrick's side close the gap on second-placed Manchester City to seven points and move three points clear of Villa in fourth.
"It is a huge achievement for me, but the main achievement will be finishing in the top spots at the end of the season," Fernandes said.
Liverpool are now two points further back in fifth after squandering victory against relegation-threatened Spurs when Richarlison struck in the 90th minute to stun the Anfield crowd.
Tottenham looked set to extend their losing run to seven games in all competitions when trailing Dominik Szoboszlai's first-half free kick but the battling draw left them one point clear of the relegation zone.
"We stayed in the game, we believed, I felt that we could score the goal, the players also felt it, so it's nice," Spurs boss Igor Tudor said.
"It's a long way to our goal, which is to stay in the Premier League, but today was important to show what they showed, independent of the result."
West Ham United's draw with City on Saturday had meant Nottingham Forest (29) dropped into the bottom three.
But they quickly climbed back out on goal difference with a 0-0 draw at home against Fulham.
15th-placed Leeds United (32) edged three points clear of the drop zone after their scoreless draw at Crystal Palace.
With PA.
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