The Belgium international completed a season-long loan move to Dortmund in the summer transfer window after the Red Devils signed Anthony Martial in a £36m deal from Ligue 1 side Monaco.
Januzaj has made four substitute appearances in the Bundesliga for Dortmund since his loan switch, while the 20-year-old has started two of their three Europa League games.
The on-loan United forward sent a message to Rooney after the Red Devils skipper turned 30 on Saturday morning.
Happy birthday wazza pic.twitter.com/Ep3Omiu0i4
— Adnan Januzaj (@adnanjanuzaj) October 24, 2015
Januzaj was still loaned out to Dortmund for the season despite having scored United’s winner in a 1-0 victory over Aston Villa in August.
The Belgian winger has scored five times in 47 top-flight games for United since making his debut under David Moyes in 2013.
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