Grealish has been strongly linked with a move to United at the end of the season, particularly if Dean Smith's side lose their battle against relegation from the Premier League.
"I think the last game they caused us some problems, Grealish off left and El Ghazi on the right," said Solskjaer.
"Grealish scored a fantastic goal. There's been loads said about him and we need to be aware of him, if he's off the left, middle or right.
"He attracts players to him but there's not just one player in that Villa team, there are a lot of them.
"They've shown since lockdown they can hold their own. They've been in tight games.
"They've worked on their shape and their counter attack is one of the most powerful in the league, they spring quickly. Set-plays as well.
"They've got some good first contact players, big size and some individual players."