The Portugal superstar's dream second debut against Newcastle seems like a distant memory.
He made an incredible start to the season, scoring four goals in his first week.
This included his two strikes against the Magpies, a Champions League goal against Young Boys and another in a 2-1 win over West Ham.
But fast forward six months and Ronaldo and the Red Devils are in turmoil.
Ole Gunnar Solskjaer has been axed, his replacement Ralf Rangnick just can't get a tune out of his players and they are now outsiders for the top-four, having drawn their last two top-flight matches and crashed out the FA Cup in February.
Ronaldo's form has also massively dropped off, with the 37-year-old currently enduring his worst goal drought since 2009.
He has failed to score in six club appearances for the first time in over a decade.
Nevertheless, Ronaldo's drought isn't even the most unsettling thing about their supersar striker at this moment in time.
Despite making his name as arguably the game's most lethal player in the air over the last two decades, Ronaldo hasn't scored a Premier League header since he returned to the club.
Questions must be asked of the service and quality of crossing within Rangnick's squad as he can't have just got bad at headers overnight.
Dean Ashton joined talkSPORT on Monday and said Ronaldo is