Messi 3-3 Ronaldo: The battle of the Champions begins again.

The Argentine and the Portuguese are the world's two finest footballers and have already ignited Europe's premier club competition this week. But who will come out on top?

Good things, it is often said, come in threes. And as the Champions League commenced again this week, the tournament's two finest footballers both hit trebles to kick off their own personal duel in the latest edition of Europe's elite club competition: Ronaldo and Messi are already off and running.

First it was Cristiano: the Portuguese marked a week in which he celebrated signing a new contract with Real Madrid by hitting a hat-trick in his side's superb 6-1 win at Galatasaray on Tuesday night, as the capital club began their quest for La Decima in impressive fashion. But Leo was not to be outdone and the Argentine struck a triple of his own as Barcelona beat Ajax 4-0 in an ultimately comfortable clash at Camp Nou a day later. Following a summer break, the Champions League is now well and truly back in the spotlight, ignited instantly by its two brightest stars.

HAT-TRICK HEROES: CR & LEO

Cristiano converted with two opportunistic efforts for Madrid in Istanbul, before completing his hat-trick with a superb solo strike which saw him beat several defenders and angle a powerful drive into the corner against an admittedly weak Galatasaray back line.

Messi, meanwhile, led a somehwat subdued Barca side to a routine win at home to Ajax on Wednesday as the Catalans went through the gears before comfortably killing off Dutch hopes of an upset in the second period. The Argentine opened the scoring with a fine free kick in what had been an evenly matched first period, slotted in a second after latching on to a Sergio Busquets ball and made it three for him personally (after Gerard Pique had headed Barca's third goal) with a low drive into the corner late in the game.

Between the two of them, Messi and Ronaldo have finished the last three seasons as top scorers in the Champions League: Leo struck 12 goals in 2010-11 and added 14 more (a new competition record) the following season, while Cristiano converted 12 times in 2012-13.

Now, with three goals apiece from just one game, the two rivals look set to dominate the scoring charts in Europe's premier club competition once again. Messi 3-3 Ronaldo: the battle of the Champions begins again in earnest.(Goal.com)