The Spanish striker was an unused substitute on his only previous visit to Manchester United when Valencia earned a 1-1 draw in the group stage of the Champions League in December, 2010.
Roberto, now with double-figure goals to his name this season, played the full game in the first meeting at the Mestalla which United won 1-0, Javier Hernandez on target.
Now he’s ready for his first Premier League outing at the ‘Theatre of Dreams’.
“I’m really looking forward to it,” said Roberto, who opened the scoring in Sunday’s 3-0 win against Stoke at the Lane.
“We played at United in the Champions League when I was at Valencia, we drew 1-1. It’s a very big game. We’re on the same points as United and if we attack them, we have a chance to beat them.”
Meanwhile, Roberto said he was thoroughly enjoying his flourishing new strike partnership with Emmanuel Adebayor – the pair set for their fourth start together at Old Trafford.
“I’ve a great partnership with Ade, we’re playing close to each other and we’re causing teams problems,” added the Spanish international.
“I think we’ll get better in the future as well.”