World Player of the Year Messi has been on fire this season for La Liga leaders Barcelona with 24 league goals, while Ronaldo is living up to his tag as the world's most expensive player with the same number of strikes for chasers Real Madrid.
"For me, it is not just about Ronaldo against Messi, but above all about Portugal against Argentina - individual duels are for the fans (to enjoy)," Portugal coach Paulo Bento said ahead of the match in Geneva.
"We have to bring out the best in Ronaldo within a team dynamic, and ensure they cannot do that with Messi," he added.
Bento took charge in September after Carlos Queiroz was sacked for insulting anti-doping agents, and has been praised for reviving Portugal's Euro 2012 qualifying hopes after a poor start with wins over Denmark and Iceland.
A 4-0 thumping of World Cup winners Spain in November showed a more attacking style than under Queiroz, and by selecting tricky winger Ricardo Quaresma for Wednesday's friendly Bento signalled he wants Portugal to show flair as they continue to build momentum.
"We want to win and play well. It is an important game to prepare the key qualifier against Norway in June," Bento said.
The game is also important for Argentina, with coach Sergio Batista using the chance to test out new players ahead of the Copa America to be played on home soil in July.
Batista said resting strikers Carlos Tevez and Sergio Aguero and defenders Gabriel Heinze and Martin Demichelis did not represent a punishment.
The coach is expected to give Velez Sarsfield forward Juan Manuel Martinez, viewed as one of the best players in the Argentine league, a debut cap.
Batista, who took over from Diego Maradona after last year's World Cup, may also use Messi in a central role in attack to test how he links up with playmaker Javier Pastore.
Probable teams:
Portugal: Eduardo; Jose Bosingwa, Ricardo Carvalho, Bruno Alves, Fabio Coentrao; Joao Moutinho, Raul Meireles, Carlos Martins; Nani, Helder Postiga, Cristiano Ronaldo.
Argentina: Sergio Romero; Pablo Zabaleta, Nicolas Burdisso, Gabriel Milito, Ezequiel Garay; Ever Banega, Javier Mascherano, Javier Pastore; Juan Manuel Martinez, Lionel Messi, Ezequiel Lavezzi
