MADRID, SPAIN - MAY 27: Cristiano Ronaldo (L) of Real Madrid CF celebrates their trophy with teammate Sergio Ramos (R) at Cibeles Square a day after winning their 13th European Cup and UEFA Champions League Final on May 27, 2018 in Madrid, Spain. (Photo by Gonzalo Arroyo Moreno/Getty Images)

4 Key Battles That Could Decide Portugal's World Cup Clash With Spain on Friday

Portugal and Spain contest one of the most highly anticipated World Cup group games this year when they meet at the Fisht Olympic Stadium on Friday.

The game has had a huge build up off the pitch, with the recent news that the Spanish Football Federation ​dismissed manager Julen Lopetegui on the eve of the tournament in Russia.

There is also plenty to look forward to on the pitch, with the attacking flair of Cristiano Ronaldo, David Silva and Marco Asensio on show.

Several key battles across the pitch could decide this match, so let's take a look at them in further detail.

1. Cristiano Ronaldo vs. Sergio Ramos

Sergio Ramos and Cristiano Ronaldo may have achieved success together on the European stage for Real Madrid this season, however, the duo will be fierce rivals throughout this summer.

The two will be in direct competition on Friday, with Ronaldo looking to get the better of his teammate Ramos, who is willing to do whatever it takes to win.

Despite their apparent friendship, this rivalry could get headed when Friday's match rolls around. This battle could hold the key to the result of the whole match.

2. Andrés Iniesta vs. William Carvalho

After an emotional final season at Barcelona, Andrés Iniesta will be looking to end this chapter of his career on a high at the World Cup.

Despite being 34, the Spanish midfielder still has a crucial part to play in his country's campaign, as he can pull the strings in midfield and has the ability to find a pass that can unlock a defence in a split second. 

He will be up against Sporting midfielder William Carvalho, known for his defensive prowess and ability to break up play. This will make for an exciting battle in the centre of the park.

3. Fernando Hierro vs. Fernando Santos

Plenty of attention will be on the touchline when these two sides meet on Friday. Spain dismissed manager Julen Lopetegui on the eve of the tournament, after clashing over the Spaniard's decision to move to Real Madrid without informing the Spanish Football Federation.

Their new manager, Fernando Hierro, has a tough task as he leads his country into the World Cup with virtually no notice.

Portugal boss Fernando Santos will have confidence leading his team into a major tournament, after his side won Euro 2016 in style two years ago. This match may boil down to a battle of wits in the technical areas.

4. Diego Costa vs. Pepe

Atlético Madrid striker Diego Costa provides Spain with a different attacking dimension, compared to the rest of the options that new boss Fernando Hierro has available. 

Costa has scored seven goals in 18 appearances for Spain since making his debut in 2014, and will be looking to have a big World Cup after only managing seven goals in 23 appearances for his club last season.

He will come up against former Real Madrid defender Pepe, who now plies his trade in Turkey with Beşiktaş. The 35-year-old is a key player for Portugal and his defensive prowess could be key to stopping the powerful Costa.