The supporters greeted Riera by lighting flares, cheering and chanting as Riera touched down in Greece in scenes more reminiscent of the arrival of a superstar such as David Beckham.
Prince Albert: Riera's car passes through crowds of fans (above) afterthe Liverpool winger (below, waving to supporters) arrived in Greece
The Reds bought Riera for £8million in 2008 but will only receive £3.3mup front for the 28-year-old with a further £1.6m if the Greek side wintheir domestic league title.
The Spaniard fell out with former Anfield boss Rafa Benitez after publicly expressing his frustration at being unable to establish himself as a first-team regular at Anfield. He has not featured for Liverpool since the club's Europa League defeat in Lille in March.
Flare enough: Olympiakos fans provide a colourful entrance for Riera (above), who found it difficult to pass through the swelling crowds (below)
The 28-year-old midfielder failed to make Spain's squad for thissummer's World Cup, although fellow Liverpool players Fernando Torresand Pepe Reina were included.
Olympiakos finished secondbehind Panathinaikos in the Greek league last season, and lost out on aChampions League spot to PAOK in the playoffs.
Rare appearance: Riera has not featured for Liverpool since March
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