Liverpool striker Fernando Torres has been ruled out for three weeks with an adductor injury, the club has said.
Alonso had only just returned from a similar metatarsal injury
Midfielder Xabi Alonso is also facing a spell on the sidelines after X-rays revealed he had fractured the fourth metatarsal in his left foot.
Both players were injured during Sunday's 1-1 draw against Arsenal, along with team-mate Javier Mascherano.
However, the Argentine midfielder has suffered only extensive bruising and no bone injury, scans have revealed.
Torres suffered a recurrence of the injury which had kept him out for a month before he played in Sunday clash at Anfield.
Alonso limped off after 68 minutes while Torres was replaced by Peter Crouch at half-time and Mascherano was left with his foot in a medical boot.
Manager Rafael Benitez said: "Alonso has suffered the same injury again, the metatarsal, he felt something go in his foot.
"Torres also has a similar injury, a problem with an abductor muscle. He could not work as hard as we wanted, we wanted his pace and it was not available.
"He just was not fit. We talked beforehand and he said he was fine. Now we must wait again, he had been out for some time and we have been pushing to get him back, but he has not been right and he still is not right.
"I will need to check with the doctor to see how the players are in the next two days."
Benitez admitted his side paid the price for the injuries they experienced during the game at Anfield.
"We had problems when we lost Torres and then Alonso. We could not control the midfield then, we also had Mascherano with a foot injury and had lost (Mohamed) Sissoko beforehand with sickness," he said.
"In the end there were too many problems against a really good team."
But he praised the contribution of his captain Steven Gerrard who netted Liverpool's goal after a difficult week.
"Stevie has been playing better and this was a very good performance," he added.
"We had a plan to use the strikers wide and for Stevie to attack through the middle with two holding players behind.
"But when we started losing players through injury, it just became too difficult to get forward.
"What pleased me most was the commitment of the players, our supporters should be happy with the efforts they put in against a very good team like Arsenal.
"Arsenal are playing well, a fantastic team. But it is too early, we are six points behind with a game in hand and there is a long way to go yet."