Gilbert showed his form by winning Sunday's 244km stage at Tirreno-Adriatico with a late surge to the line, while the Greipel has recovered from the facial injuries he suffered while warming up for the opening team time trial in the Italian stage race.
Gilbert has already won three races this season, having taken the opening stage of the Volta ao Algarve and the Montepaschi Strade Bianchi, before the fifth stage of Tirreno-Adriatico.
Despite his pre-race crash, Greipel rode the team time trial stage with his face covered in bandages but the next day the team pulled him out of the race.
“My injuries are healing well, and I've been able to train properly again in the last few days,” he wrote on his personal website.
The German flew home from Italy for further examinations in Cologne, Germany, which showed that he had not suffered any facial fractures.
He will ride the Nokere-Koerse one-day race in Belgium on Wednesday before leaving for Italy. He finished third in that race in 2008.
This will be Greipel's first appearance at Milan-San Remo after being overlooked for a place for the race by his previous team HTC-Columbia, who preferred to select Mark Cavendish as the protected sprinter. Cavendish won Milan-San Remo at the first attempt in 2009.
The Omega Pharma-Lotto line-up for Milan-San Remo: Philippe Gilbert, Andre Greipel, Adam Hansen, Sebastian Lang, Vicente Reynes, Jürgen Roelandts, Marcel Sieberg, and Jussi Veikkanen.