SCORING 43 goals in 40 games would be a significant statement of intent by most standards, but with El Clasico on the horizon, Lionel Messi decided to go further.

On Wednesday, the Argentine produced a European performance so impressive it made elite-level professionals look like amateurs, dribbling and nutmegging Manchester City players at will as if operating in a different field of gravity. As Camp Nou gasped in admiration, one can only imagine what a certain Cristiano Ronaldo must have thought, the Ballon d'Or winner no doubt keeping a close eye on the player that pushes him hardest. Only two months have passed since Ronaldo was named world player of the year, yet this week, the sporting press is once again filled with talk of Messi being the greatest ever. How his nemesis responds will crystallise on Sunday, when the pair meet face-to-face in the latest edition of football's most compelling rivalry.

Much has changed since Barcelona and Real Madrid last clashed. Madrid's 3-1 win in October showed off the best of Carlo Ancelotti's side, a combination of clearly defined tactics, physical prowess and technical finesse overwhelming Barça at the Bernabeu. For the Catalans, who had gone unbeaten in their first eight league fixtures, losing so resoundingly was a significant blow. Sluggish in midfield and lacking penetration in the final third, even Messi was quiet, Ronaldo requiring little more than a penalty goal to outshine his old foe.

At that moment the Portuguese was in the midst of an astounding run of 20 goals in 12 league games, hitting what used to be considered strong end of season numbers in a matter of only three months. Messi, meanwhile, had scored less than half as many, his seven La Liga strikes decent but not quite up to the extraterrestrial level we have become accustomed to from these two. The Barça forward continued to live in Ronaldo's shadow going into the New Year, a situation he had been forced to deal with since the Madrid man was voted the best player on the planet in January 2013.

Ironically, Ronaldo's third such award, handed to him a year later, has served as the perfect motivational tool for Messi to displace him once more. If you believe the Barcelona press, the humiliation of watching on in Zurich as his opponent delivered a brash acceptance speech gave Messi the impetus to ensure he would never be put in that position again. Spotted training for hours at Barcelona's sporting complex during his post-January days off, he has shed around three and a half kilos and recovered the explosiveness of old.

The result of the hard graft is a dramatic upturn in efficiency. Putting away 17 strikes in the last 11 La Liga games, three more in El Clasico would see Messi match Ronaldo's feat of 20 in the space of 12 league fixtures. The Barcelona man's last treble against Los Blancos came during his supposed annus horribilis of 2014, so doing the same this Sunday wouldn't be unthinkable. Particularly as he is now just as likely to score on his right foot as his left: 12 of the Argentine's goals this season were finished on his weak side, including a Champions League hat trick. As good an indicator as any of his renewed thirst to continue improving.

Worryingly for Madrid, even when Messi isn't scoring, he has still been decisive. After abandoning the false nine position that brought him glory under Pep Guardiola, a move back to the right wing has allowed him to receive the ball facing goal and in space. Manchester City discovered just how effective that shift has been on Wednesday night, when Messi frequently danced past assailants on the bye-line, threading diagonal balls into the area. "He's the best, and if he's not the best, well . . .", Joe Hart said despairingly in the post-match mixed zone.

As if the two are part of some grand footballing equation that requires balance, Messi's ascension has coincided with a significant drop from Ronaldo. He has only scored twice in La Liga since January; of those two goals, one was a penalty, and the other a header. The latter is a reflection of his notably reduced mobility in recent months, the Madrid forward's only impact on games coming within the box, and even then, infrequently. While Ronaldo was top scorer in La Liga going in to March, his dry patch combined with Messi's explosion has seen that change. He now trails the Argentine's 32 goals by two.

On Wednesday, Messi suggested his turnaround hasn't been quite as dramatic as some would insist. "I've gone from being a disaster to being in my best form ever in a very short period of time" he noted ironically. Perhaps he is right to calm the hysteria: driven by envy, Ronaldo could well produce a similar recovery of his own. Madrid fans will hope that starts at Camp Nou.