Militao, who can also play at right-back and has been capped once by Brazil, reinforces a Real defence that has often been diminished by injuries this season.
United were paired with Barcelona in Friday's Champions League quarter-final draw, and Solskjaer believes that the previous round's away-goals win over Paris Saint-Germain showcased numerous qualities United will need to progress to the last four of the competition.
Zinedine Zidane takes charge of his first game since making an astonishing return to Real Madrid on Saturday against Celta Vigo which is set to be a de facto audition for next season for numerous team's underperforming players.
Another player Zidane said he would "count on" is Isco, who on Friday was left out of Luis Enrique's Spain squad having made only one start for Real so far in 2019.
"I think we've shown against PSG that on any given day we can beat a top team".
According to Metro, the Portuguese tactician, who was sent packing by Man United mid-December was close to a return to the Santiago Bernabeu after talks with Madrid president Florentino Perez.
"We are playing this season".
"I saw a good, happy Gareth Bale, even if there has been some problems on the pitch", Poyet told The Debate on Sky Sports. "We are ready, he is ready", said Zidane. What I can tell you is that these two players have a lot of quality.
Real lie third in the LaLiga table, 12 points behind leaders Barca.