Having grown up as an Evertonian before becoming a Manchester United legend, Rooney is struggling to come to terms with the fact that the Reds are competing with City to win the title.
The DC United forward told talkSPORT: "It's a great reason to be out the country when those two are going head to head for the title.
"I hope Man City get over the line before Liverpool. I couldn't bear to see them win it, it would be a nightmare for any Evertonian.
"I remember in 2005 they won the Champions League and they're still talking about it now so it would be another 10 or 15 years of that!"