England duo Steven Gerrard and Jamie Carragher sealed new four-year deals tying them to Anfield until 2011 on Monday, but Benitez could have more trouble keeping Alonso as he prepares for the new season.
Reina seems certain to extend his deal, as does full-back Steve Finnan, but speculation from Spain suggests Alonso is seriously considering a move to Barcelona.
Benitez, who returns from holiday at the end of the week, aims to move heaven and earth to prevent Alonso's departure, but that deal is the most worrying point as he attempts to keep a string of senior men at Anfield.
The contracts for Gerrard and Carragher were much easier to secure, the two local lads signing together at Anfield having slipped away from England's training camp in Manchester to complete the formalities.
Carragher is desperate to still be in the Liverpool first team when the new Anfield is opened, maybe in four years' time when he will be 33.
He said: "The contract takes me through to 2011 and, hopefully, Liverpool will be playing in a new stadium by then.
"That would be nice. I think it's been put back a year and hopefully the new plans will make it even better.
"I'm a bit older than Stevie so my aim is to still be in the team by the time we get to the new stadium.
"I think it's going to be brilliant for everyone - the players, the club and the supporters.
"My aim, as I said, is to still be a regular for Liverpool by the time we get to a new stadium."
Gerrard believes that their decision to stay is a clear sign that the future is bright at Anfield.
He said: "You've seen off the field that the club is wanting to move forward in the right direction.
"It's the same for the players and we want to back that up by delivering big performances on the pitch to make sure the club continues to be successful for years to come.
"It's no good all of the things happening right off the pitch if the players don't deliver on it.
"That's where me and Jamie and the other boys come in and hopefully we can back that up with the way we play.
"I think it's a good statement from the club to show that they are signing big players for a long time."