Victory will all but clinch Chelsea's place in next season's Champions League but Benitez believes improving Villa will provide a stern test especially as the home team's relegation fears have not yet been completely dispelled.
"I don't think it matters what happened in the game at Stamford Bridge," the Spaniard told a news conference. "They want to win, they need to win.
"We've seen their last few games, they are doing well and it will be tough because they want to stay in the Premier League."
Chelsea are third in the table, two points in front of Arsenal and three ahead of fifth-placed Tottenham Hotspur with two games to go.
The top three qualify automatically for the Champions League and the team in fourth goes through to the preliminary round.
Benitez rested Frank Lampard for Wednesday's 2-2 draw with Tottenham and said the England midfielder would definitely return against 13th-placed Villa who are five points clear of the drop zone.
The European champions, though, have injury concerns about wingers Eden Hazard and Victor Moses.
Benitez wants three points from Saturday's lunchtime kick-off so that the belief of his players is strong going into Wednesday's Europa League final against Benfica in Amsterdam.
"If we can win against Villa it will be easier to approach the final with confidence," he explained.
