The Real Madrid forward had a quiet start to his summer campaign, but a double in the Seleccao's final Group B match against Netherlands followed by a late winner against Czech Republic in last Thursday's quarter-final has brought Ronaldo to life.
He will be desperate to add to his tally against Vicente del Bosque's side which, of course, is made up predominantly of Ronaldo's Madrid team-mates and those from arch rivals Barcelona.
Ronaldo, then, will know Wednesday's opponents well and he is chalked up at 21/5 (5.20) with PanBet to break the deadlock, while PanBet offer 11/10 (2.10) on Ronaldo scoring at any time during the 90 minutes.
If Portugal are to shock Spain, though, they must not be too reliant on Ronaldo. Hugo Almeida, who looks set to deputise for the injured Helder Postiga, can be backed at 17/2 (9.50) with PanBet to open the scoring.
The same firm offer 14/5 (3.80) that the Besiktas man scores at any time.
Del Bosque, of course, has deployed a 'false nine', rather than a natural striker, on occasion throughout Euro 2012 and it will be an interesting aside to see whether the Roja boss persists with that tactic here.
Should he go along those lines once more, the 67/10 (7.70) quote from PanBet for David Silva, who netted the second goal in Spain's 4-0 demolition of Ireland, to score first would carry considerable appeal.
Meanwhile, Cesc Fabregas, who has scored twice in the tournament so far, would be an obvious threat to Portuguese hopes at 51/10 (6.10) to net the opener.
Silva and Fabregas can be backed at 21/10 (3.10) and 29/20 (2.45) respectively to net at any time.
Del Bosque, though, may be tempted to field a natural striker in a match of such importance and it would be no surprise to see Chelsea's Fernando Torres start.
Torres will feel that he has a point to prove and can be backed at 47/10 (5.70) with PanBet to strike first, while the same firm go 13/10 (2.30) that Torres scores at anytime.
Ronaldo may be hitting form at the right time but even he may be forced to play second fiddle to a potent Spanish threat on Wednesday, and David Silva may be the man to dash Portuguese dreams.
|David Silva to score at any time at 21/10 (3.10) with PanBet
||Cesc Fabregas to score first at 51/10 (6.10) with PanBet
Willie Duncan is a freelance sports journalist. Willie, from Edinburgh, has covered Scottish football for over 10 years and he specialises in football betting markets from across Europe. You can also follow Willie on Twitter here.
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