By Iain Rogers
BRASILIA, July 3 (Reuters) - Argentina's World Cup quarter-final against Belgium on Saturday is likely to be decided by who comes out on top in a continuing duel between their captain Lionel Messi and opposing goalkeeper Thibaut Courtois.
Barcelona forward Messi, whose four goals and one assist have propelled the South Americans into the last eight, has faced Courtois 10 times in three seasons since the lanky 22-year-old joined Atletico Madrid on loan from Chelsea in 2011.
Courtois has been solid rather than spectacular, making 11 saves in Belgium's four games compared with 29 by United States stopper Tim Howard, though he did produce a brilliant block to deny U.S. forward Clint Dempsey late in their last-16 clash.
Messi came out firmly on top in his early encounters with Courtois in Spain, netting six goals in their opening three games including a brilliant hat-trick in the first meeting, a La Liga match in September 2011 that Barca won 5-0.
The third of Messi's treble left the young keeper on the seat of his pants after the four-times World Player of the Year cracked the ball straight between his legs from a tight angle on the left of the penalty area.
Messi made Courtois look foolish again for his next goal, a crafty free kick in a 2-1 La Liga victory for Barca at Atletico's Calderon stadium in February 2012.
The Belgian was still adjusting his wall and out of position when Messi, who had not asked for the Atletico players to retreat and did not need to wait for the referee to restart play, clipped the ball over the barrier and Courtois could only watch helplessly as it sailed into the far corner of the net.
Courtois must have been wondering what had hit him when Messi struck a double in a 4-1 home win for Barca in December 2012 but that was the last time the Argentine found the net against the Madrid club.
He went off injured with about 20 minutes left in their La Liga game in May 2013 before they faced each other six times last term across the Spanish Super Cup, domestic league and the Champions League and Messi was unable to add to his tally.
He came closest to scoring in the return leg of the Super Cup when he struck a penalty against the crossbar but Courtois and his team mates otherwise kept him at bay as Barca ended the season without major silverware for the first time in six years.
After an indifferent season by Messi's high standards, when he missed two months through injury, the diminutive forward looks close to his scintillating best in Brazil.
The 27-year-old is the bookmakers' favourite to win the Golden Boot for leading scorer and the Golden Ball for player of the tournament.
He is one goal behind Colombia's James Rodriguez on the list of top marksman and appears to be carrying a mediocre Argentina side in much the same way as his predecessor as captain Diego Maradona did in his pomp.
Whether Messi can help them beat the Belgians, who lost 2-0 to Argentina in the 1986 semi-finals with Maradona netting both goals, will depend on him breaking his unusual scoring drought against one of the most promising young keepers in the game.
Jean-Marie Pfaff was in goal for Belgium for the match in Mexico nearly three decades ago but was unable to thwart Maradona and current coach Marc Wilmots knows the scale of the task facing Courtois on Saturday.
"It's clear that it will be very difficult for us if Messi is on form but we have found the balance to be able to irritate Argentina," he told a news conference on Thursday.
The winners will play the Netherlands or Costa Rica in the last four. (Editing by Ken Ferris)