From various leaks or comments then it seems the starting line-up is clear except for who plays alongside Henderson - Gerrard or Allen. With a midfield pairing of Mason and Bentaleb to face (not to mention the shackling of Eriksen) you've got to imagine it will be Allen. It just makes so much more sense to bring Gerrard on later if we need a goal and give him half an hour to play at 100%.
It's also true that if Gerrard starts he is unlikely to be subbed, and could well be a bit of a passenger for the last 20-30 mins, which does neither him nor the team no favours. It would be great to see him coming on, à la Lampard, and flourishing in that role. Time will tell.