Sinclair had hoped for a return from a knee injury this weekend, but his omission gives D'Laryea the opportunity to gain some valuable experience following an impressive run in the reserves.
"I haven't put Trevor in the squad as he was not in on Friday as he has got some sort of flu," Kevin Keegan told the City website.
"I've brought Jonathan into the squad and he has been the only addition since last week. He has done very well in the reserves, and needs must, I suppose, but we must give credit to the young players here.
"They have looked at the squad and saw that they have a chance and decided to do something about it. What they are doing is really pleasing. Willo Flood has broken through and nothing can stop Nedum Onouha. It is just a question of when for him."
City's midfield is depleted with Sinclair joining Claudio Reyna and Joey Barton on the sidelines, so Steve McManaman will play in the centre, alongside Paul Bosvelt, with Antoine Sibierski used at left-midfield.
"Steve has recovered from the problem with his Achilles and he is fine now," added the City boss.
"He's waited for his chance. It is his last year here and he still has a lot to give this club. I still have full confidence in him.
"I thought he did really well when he came on against Chelsea which was not an easy game to come on in."