After a poor first-half display, with Atalanta taking a 2-0 lead in at the break, Ole Gunnar Solskjaer's team turned the game -- and possibly their season -- around with a thunderous performance.
Everton had a goal ruled out for offside by VAR after Townsend cancelled out Martial's opener.
On the night he set the new record for the most appearances in the competition, the 36-year-old delivered the killer blow to save his manager Ole Gunnar Solskjaer from another disappointing result.
Ronaldo is set to make $125 million before taxes in the 2021-22 season.
Cristiano Ronaldo scored his fourth goal in three games.
Manchester United crushed Newcastle United 4-1 with Bruno Fernandes and Jesse Lingard adding a goal each.
Kuwait-based Shahzad Mohammed Rafi, 17, is one of the seven freestyle footballers selected to the '2021 Red Bull Neymar Jr's Five World Final' via Instagram entries from the world over.
Ronaldo went past Iranian Ali Daei's total of 109 international goals.
The Portuguese superstar dedicates his Manchester United return to former boss Alex Ferguson.
Financial details of the transfer were not disclosed but British and Italian media reported United signed Ronaldo for 25 million euros.