The Spain international passed his medical in Madrid today - the final hurdle before completing his £30million transfer to Real.

Benitez began the search for a suitable replacement in May when the 27-year-old informed him he felt his future was away from Anfield.

The Liverpool boss is reknowned as a meticulous planner and would have had a list of options to hand but he has held off making any move until he was sure Alonso would leave and what transfer fee would be forthcoming.

"We would have liked to have kept him but as soon as he told us that he wanted to leave we started working, looking for players and trying to do the best deal for the club," said Benitez.

"It has been too long, since May, that he told us he wanted to leave and after the official transfer request we were working very hard.

"The first idea was to keep him, and the second one was to find the best price and the best replacement for us."

Reports suggest Roma's Alberto Aquilani is the man Liverpool have lined up as a £16million replacement, although the 25-year-old will have to prove his fitness first.

The Italy international has not played since March - having made only 14 league appearances all season - and underwent surgery on his right ankle in May.

Whoever Benitez brings in will find it difficult to slot seamlessly into the side with their Barclays Premier League season opener at Tottenham just 10 days away.

Former Liverpool midfielder Jan Molby believes it will be nearly impossible to fill the hole left by the departure of Alonso.

"Liverpool will miss him a lot. You talk about key players and although Fernando Torres and Steven Gerrard are the two most important players in the team just behind them is Alonso," he told Radio 5 Live.

"He is the one who directs the tempo of play. That ability to spot a pass to give Gerrard a split second on the ball to do his stuff will be a big loss to Steven.

"In the last 12 months he has been as good as anyone at Anfield but for some reason the manager has decided he wanted to do something else and that Alonso was always going to be available and now he has got his £30million he needs to go and spend wisely."

Benitez may use some proceeds from the Alonso sale to bolster central defence as Daniel Agger and Martin Skrtel have both been struggling with injuries in pre-season.

Skrtel is currently recovering from a hamstring strain sustained in the friendly in Thailand while Agger has a back problem.

However, former striker Ian Rush believes his old club need to invest in some creativity.

"The problem Liverpool could have is if Fernando Torres gets injured again - Liverpool missed him last year when he was out," Rush said.

"If Rafa adds maybe three players, left and right and possibly a striker, Liverpool can go one better (than last season's second place.

"If they don't add a striker maybe they will look to someone like Ryan Babel to come through this year.

"He's been at the club long enough to bed in. Now it's time to take responsibility and produce."