Lampard has 22 players in his squad for the win at the Madjeski, which saw youngster Mason Mount nab an impressive brace.
Speaking after the game, Lampard said: "I wouldn't say I've made decisions yet in terms of selection for those early games or what the squad looks like because that's a line and I don't want to draw that line just yet.
"There's not a player who hasn't pushed themselves and shown me everything but these are decisions I have to make. They're not absolutely clear decisions but I'll make them in due course.
On preseason as a whole, Lampard has been impressed with the hard work shown by his players.
He added: "The players have done everything that we as staff have asked of them. We've had two good trips – one to Dublin which was purely work and the boys worked brilliantly, and then Japan to see the fans over there and play two very tough games so that was also great for us.
"The clock is ticking and we only have two weeks left to be ready for Manchester United but I'm pleased."