Over the years, Liverpool have made a number of double transfer swoops with varying degrees of success.

John Barnes and Peter Beardsley in the summer of 1987, Luis Suarez and Andy Carroll in the January window of 2011 and, er, Jerzy Dudek and Chris Kirkland on the same day in September 2001.

But few can match the impact of the Spanish duo whose signings were announced fifteen years ago today.

On 20 August 2004, new Liverpool manager Rafa Benitez was 24 hours away from making his Anfield debut as manager with Manchester City due in L4 for the first home Premier League game of the season, following the opening weekend's 1-1 draw at Tottenham.

Xabi Alonso and Luis Garcia sign for Liverpool
Xabi Alonso and Luis Garcia sign for Liverpool

The summer of 2004 had seen Liverpool break the club's transfer record when £14m was shelled out for French striker Djibril Cisse but the deal had been lined up during Gerard Houllier's reign and, aside from the low-key captures of his compatriots Josemi and Antonio Nunez (as part of the Michael Owen to Read Madrid deal), there was a feeling that Liverpool's new Spanish manager hadn't yet been allowed to bolster his squad as fans would have hoped and expected.

That was until it was announced Liverpool had completed the signings of Xabi Alonso from Real Sociedad for £10m and Luis Garcia from Barcelona for £6m.

Aside from die-hard La Liga afficianados, most Liverpool fans didn't really know who their new Iberian acquisitions were but placed their faith in their new leader and hoped the two young bucks he'd imported from his homeland - Alonso was just 22 when he arrived at Anfield, Garcia was 26 - would spark a bright new era at Anfield. And did they ever...

Xabi Alonso and Luis Garcia sign for Liverpool
Xabi Alonso and Luis Garcia sign for Liverpool

It wasn't the most auspicious of starts for the Spanish duo, both making their debuts in an infuriating 1-0 defeat to Bolton inspired by Sam Allardyce's agricultural tactics and Kevin Davies' elbows - Garcia having an equaliser incorrectly chalked off for offside in the second half - but within a few weeks the Anfield crowd had enjoyed their first couple of looks at them.. and very much liked what it saw.

A pair of 3-0 wins a fortnight apart against West Brom and Norwich saw grown men swooning in the stands and whispering about Jan Molby after witnessing the range of Alonso's passing while Garcia served notice of his eye for goal by finding the net in both matches.

As winter kicked in, Alonso began to rapidly underline his value to Benitez's side following up his first goal for the club - a deflected free kick at Fulham as the 10-man Reds (after Josemi got sent off) recovered from two goals down at half time - with a sensational first Anfield goal as champions Arsenal, beaten only once in their previous 54 league matches, were felled by Neil Mellor's long-range last-minute strike.

Xabi Alonso of Liverpool scores the first goal during the Barclays Premiership match between Liverpool and Arsenal at Anfield on November 28, 2004

The jury was still out for some fans on Garcia however, the diminutive Spaniard's knack of finding the net being offset by perceived teething troubles with the physicality of the English game and his habit of occasionally losing the ball when trying innovative flicks and tricks to find space.

His turning point came in the Anfield derby of March 2005. Liverpool had been chasing David Moyes' high-flyers down in pursuit of fourth place - and a Champions League spot - for much of the campaign and, having been beaten by Lee Carsley's goal at Goodison in the December, knew victory at Anfield was essential to their hopes of clawing the Blues back as well as their own self-belief, with the Reds having been drawn to face Juventus in the quarter-finals of the Champions League only two days before the Anfield showdown.

Benitez's men came flying out of the traps and established a two-goal lead within half an hour thanks to a Steven Gerrard free-kick and Garcia himself again showing alertness to react quickest after Fernando Morientes' long-range strike had looped against the bar to nod in a second.

Luis Garcia puts Liverpool two up against Everton in 2005
Luis Garcia puts Liverpool two up against Everton in 2005

Everton's 'robust' approach however saw Liverpool needing to make three substitutions before half time and when Garcia went down as well shortly before the break, there were fears the Reds may have to struggle on with ten men.

Garcia returned from the second half though, clearly hampered by a knock but determined to help see his side over the line in such a crucial match, and proved to those who had questioned his stomach for the fight when the chips were really down (such as this observer) what he was really made of, the Reds eventually squeezing home 2-1 in the end.

And the rest, as they say, is history.

Weeks later, Garcia wowed Anfield with a sensational long-range strike as Juventus were beaten in the Champions League and then of course bagged arguably Anfield's most controversial goal of all time as he shepherded the ball in the direction of the Chelsea net and ultimately the Reds to Istanbul and footballing immortality.

Football - Liverpool v Chelsea UEFA Champions League Semi Final Second Leg - Anfield - 3/5/05 Liverpool's Javier Luis Garcia celebrates his goal Credit: Action Images / Michael Regan

Alonso meanwhile had suffered a testing start to 2005, having his leg broken by Frank Lampard in Chelsea's New Year's Day Premier League win at Anfield, and making his return in the Stadio delle Alpi as Liverpool ground out the goalless draw they needed against Juventus to reach the Champions League semis, only to be denied the opportunity to play in the biggest game of his life so far - the second leg at Anfield - by Eidur Gudjohnson's theatrics in the first leg at Stamford Bridge which saw him pick up a booking and one-match suspension.

His mate Garcia helped him out though, grabbing the 'ghost goal' which will forever torment Mourinho and Chelsea to send the Reds to Istanbul and when Alonso stood 12 yards from goal in the Ataturk stadium with the chance to unbelievably draw Liverpool level from three down against AC Milan, who was at his side as he reacted to Dida's initial save from the spot-kick?

Xabi Alonso equalises against AC Milan in Istanbul - with Luis Garcia right by his side

His partner in crime, Luis Garcia. Rafa's Spanish conquistadors, who within the space of nine months had taken Liverpool from Bolton Wanderers' punching bags to five-times Champions of Europe.