Will be curious to see how both sides set-up tactically, judging from LVG's pre-match comments he may err on the side of caution and adopt a more defensive pragmatic approach more in line with your earlier performances prior to the Arsenal game. This in large part would effectively stifle us as we haven't looked convincing breaking teams down thus far. (Barring wonder goals).
Our defence since the 3-4-3 formation switch has been largely impeccable, and as long as Can,Skrtel and Sakho are in there i expect us to be fairly comfortable, barring a complete breakdown. If United do utilise the long diagonals to Fellaini tactic, I expect Can to deal with it and if not he'll likely switch places with Skrtel to combat the threat.
One of the more interesting things in Mondays dull affair against Swansea was the introduction of a midfield diamond at half-time with Gerrard at the base, Allen and Henderson at the sides, Coutinho at the tip and Sterling and Lallana pushed up alongside Sturridge. This allowed us to shoehorn Gerrard back in to the side, give Henderson license to make runs beyond the striker, something neither Lallana or Coutinho provide and get more bodies closer to Sturridge who has looked increasingly isolated up front.
However i expect Gerrard will start from the bench, sentiments must be put aside in fixtures with as much riding on them as this.
The key to stopping United will be to limit there chances, for as much stick as they receive both Rvp and I believe Rooney to, post an above average conversion rate, this United side doesn't need many chances to score as Spurs witnessed first hand. Overall I'm looking forward to a enthralling game which I sincerely hope delivers, may the best team win.