----------------Lukaku------------------
----Rash/Martial------------Mkhi-------
Young----Matic----Herrera----Valencia
-----Jones----Smalling----Bailly--------
While I expect Mkhi for one of Rashford/Martial, I think there is a chance of seeing both Rashford and Martial.
Key factors that this 3-4-3 system with both Rash and Martial could work
1. Expect a high intensity, high pace, and very direct game.
2. Play our "best" players, especially super on form Martial and Rashford. We don't have to play unfit/lack of game time Pogba/Carrick/whoever, if available, for the purpose of fielding three in the midfield in 4-3-3/3-5-2
3. Matic and Herrera will be mainly defending and winning the ball back, without going offensive most of the time, and releasing the ball as quick and direct as possible and staying in position to defend against counter.
4. As soon as Rash/Martial/Lukaku gets the ball, plus one/two wingbacks depending on situation, they can counter directly without the need of Mkhi/Mata playmaking. All of them have pace. Besides, they all have different style. Rashford can attack the space, Martial can dribble past defenders and Lukaku can use his power. Liverpool's weak defense definitely benefits us from this perspective. Their nightmare would be one mistake then one of our attackers will be through to the box.
5. Since we don't have Pogba/Fellaini (maybe a just-fit-Carrick), the game plan is to play to our strengths of both defense and counter. The key is not to hold the ball for too long to reduce the risk of being countered. We can "skip" the playmaking in midfield and counter very, very directly with very lethal Martial/Rash/Lukaku plus one/two wingbacks as soon as we have the ball, while sitting back with both CM, three CB, and one/two wingbacks depending on situation.
6. Rash and Martial can help defending if necessary, acting as the "3rd" midfielder, while still leaving the game plan exactly the same with one of Rash/Martial and Lukaku up front.
Jose surprised us with 3-5-2 against Chelsea, with Rashford and Lingard up front, without Mkhi/Mata. The game plan for the Rashford and Lingard was to play a very direct counter as soon as they got the ball. I can see similarity in this case with both Rash/Martial.