Manchester City was drawn against Villarreal. It was not immediately clear if United's ball was put back into the draw, which would have led to them facing Atlante Madrid. The draw placed the Reds in the same group as Atleti. The LaLiga side drew a team.
The validity of the draw has been contacted by ESPN.
In the group stage of the European competition last season, Messi andRonaldo faced each other, with the Portugal international scoring twice as the Bianconeri won.
The two teams faced each other at the same stage of the season where United advanced to the quarterfinals after a win at the Paris club.
The French giants earned a 2-0 win at Old United in the first leg, but United shocked them with a Romelu Lukaku double and a Marcus Rashford penalty in Paris to go through.
When United were knocked out of the competition during the group stages, Paris Saint-Germain avenged their elimination with a 3-1 win at Old United.
Messi has won the competition four times, but is trying to win his sixth and second at United.
Last month, Messi picked up a record-seventh Ballon d'Or trophy, and five times has won the award.
In the next round, the winner of the tie between Atleti Madrid and the winner of the match between the two German teams will face off.
In the group stages, the only blemish on the record was a loss at Porto, but in the knockout stages, the only blemish was a win at Porto.
Manchester City will face FC Salzburg while FC Salzburg will face Manchester City.
After defeating Barcelona, Benfica will play Real Madrid in the knockout stages.
Lille finished second in their group and will face the holders of the European title.
Inter Milan will play an in-form Ajax side.
Group winners will be away in the first leg. Return legs will be played on March 8.
The away goals rule has been abolished in European tournament knockout ties.
The rule was used to determine the winner when teams were level on aggregate after a two-legged match. The team that scored more goals won. Extra time and penalties will replace this.
The semifinals and quarterfinals will be drawn on the same day in March.
The final will be held in Saint Petersburg, Russia.
There is a round-of-16 draw.
Real Madrid vs. Benfica.
Manchester City vs. Villarreal.
The game is between Atleti Madrid and Bayern Munich.
FC Salzburg is playing a game againstLiverpool.
Inter Milan is playing a game.
The game is between Sporting CP and Juventus.
The game is between Chelsea and Lille.
Manchester United vs. Paris Saint-Germain.
