The winger was outstanding in the 4-2 defeat of Bayer Leverkusen in midweek and scored the final goal after creating Robin van Persie's hooked effort that regained the lead for the Reds.
Valencia spoke to MUTV and explained the motivation behind his decision to change numbers. Both David Moyes and Sir Alex Ferguson feel the wide man has benefited psychologically from ditching the no.7 jersey vacated by Michael Owen's departure in 2012.
"I think it turned out to be a very good number for me when I first arrived at the club as I was just given the no.25 more or less," he said.
"But things went really, really well. I played well wearing that shirt so I think it was a decision I came to in the summer. Maybe if I can get back to the form I showed before, why not? It is a good idea to start wearing it again.
"It had been something I had been thinking about for quite a long time. I'd been considering a change back and maybe it is psychological or maybe it is just all about a good-luck symbol, if you like. We get a lot of that in Ecuador, maybe superstition, and l hope it continues and still brings me more good luck this season."