It has been a debate that has split football fans the world over for years and the arguments will resurface when Lionel Messi and Cristiano Ronaldo feature in La Liga's opening weekend.

Players, pundits, supporters and team-mates have all waded in to have their say on who is the world's best player, Barcelona star Messi or Real Madrid hero Ronaldo.

While a definitive answer is unlikely to ever be given on that front, one certainty is that both phenomenal talents will be the driving forces behind Barca and Real's quest for domestic and European glory again this season.

On an individual basis, the pair have won the last seven FIFA Ballons d'Or with Messi's four to Ronaldo's three, although the latter has collected the last two.

Most would consider Messi the favourite to win the award this time around, though, after the Argentina international enjoyed an unbelievable year to help Barca to a Liga, Copa del Rey and UEFA Champions League treble.

Messi rebounded from an injury-disrupted 2013-14 campaign in which he scored "only" 28 league goals to be the driving force behind the club's success.

He scored an impressive 58 goals in all competitions, but Messi was undoubtedly helped by the weight of expectation being shared with Luis Suarez and Neymar - the trio scoring 122 times, a record in Spanish football, and their understanding is again key for the Catalans this season.

Messi put an early season falling out with Luis Enrique to one side to score 35 of his goals after the turn of the year, but also showed that there is more to his genius than just his goalscoring prowess.

He provided 18 assists in La Liga as well as creating 95 chances for his team-mates, and there is nothing to suggest that he cannot match, or even better, those statistics this time around.

The task for Ronaldo will be to spearhead a Real side hurting from watching their great rivals steal the limelight last term and reclaiming the Copa and Champions League titles the capital club won in 2014.

The Portugal star has had to face up to a belief in some quarters that his star is on the wane, a claim that looks absurd against a staggering 48 league goals last term.

Ronaldo's critics would suggest that his goal return is a sign of his selfish style of play, but the former Manchester United forward's assists (16) and chances created (75) were statistically his best in the last five seasons - including the last time Real won the title in 2011-12 - going some way to dispelling that myth.

An important factor for Ronaldo, and Real, is his relationship with new head coach Rafael Benitez.

The Spanish press seized upon Ronaldo seemingly reacting angrily to Benitez in training last month, sparking rumours of a rift with the former Liverpool boss.

Outwardly, Benitez laughed off any suggestions of a falling out with his star man, but the vultures are sure to circle if Ronaldo has a dip in form.

Another key component will be the cohesion of Real's front three, and Ronaldo will need Gareth Bale and Karim Benzema to help share the burden this season.

Bale (13) and Benzema (15) scored 28 league goals between them last term, with the former facing fierce criticism from the media and fans alike during an underwhelming second season in Spain.

Injuries to creative sparks Luka Modric and James Rodriguez perhaps goes someway to explaining why the three did not always appear to be on the same page.

But if Real are to challenge Barca, and Ronaldo is to outshine Messi, then striking a balance for the trio is crucial.

Barcelona or Real Madrid will win the league - it would take a brave man to bet against that. Who finishes top could well come down to the victor in the latest chapter of the battle between the finest two players of a generation.