Portugal were defeated by Spain in the Round of 16 after Mikel Merino's 91st minute winner saw Cristiano Ronaldo's last World Cup campaign come to an end.

Although the match will not go down as a World Cup classic, it was an entertaining watch for the neutral, with all the quality from both sides on show. It could be the last time we see Cristiano Ronaldo for Portugal, with it certainly being his last World Cup match, but Spain advance through to the quarter-finals where they will be the favourites against either Belgium or USA.

The match was cagey in the early stages, with neither side pressing too high and trying to defend securely. Portugal sat deeper, letting Spain have the ball more, looking for opportunities to counterattack. 

The first big chance came in the 8th minute when Dani Olmo found Mikel Oyarzabal in behind the Portuguese defence. One-on-one with Diogo Costa, it looked like Spain would open the scoring, but Oyarzabal's shot rolled past the post and out for a goal kick.

Spain had another big opportunity in the 16th minute but were denied twice by Costa. Lamine Yamal's curler was pushed away by Costa and then it was Alex Baena whose effort was brilliantly tipped past the post.

There were calls for a Portugal penalty as Ronaldo fell to the ground as Rodri looked to have pulled his shirt. But, the referee did not see a foul and neither did VAR, despite the contrasting opinions of many viewers.

Portugal's biggest chances came later in the half. Ronaldo had a difficult chance but could not convert and Nuno Mendes had a shot deflected onto the crossbar. However, both sides went into the break goalless.

The second half was more quiet as both teams made sure to stop the other from scoring. Portugal were dealt a huge blow in the 55th minute when Nuno Mendes was substituted due to injury. The left-back had been one of their best players up until that point, getting the better of Yamal, but was forced to leave the pitch.

As the second half went on, both teams searched for a winner but couldn't quite edge ahead. Portugal had their moments of possession but Spain began to look the more likely to score. Mikel Merino and Ferran Torres came off the bench to make a big impact in attack, with Portugal struggling to create chances. 

As extra-time loomed, both sides tried to hold on but the breakthrough finally came for Spain, much to the disappointment of Portugal fans. Torres played a delicate pass through to Merino who calmly slotted it past Costa to give Spain a late lead. 

Portugal then threw everything they had for the final few minutes of stoppage time, but they couldn't find an equaliser. Bernardo Silva came close with a header but it wasn't meant to be for Portugal and Ronaldo.

A 1-0 win for Spain means they have become the first team in World Cup history to keep six consecutive clean sheets at the tournament. Tonight's test was their toughest yet but they showed great resilience to find a late winner.

Mikel Merino will earn the headlines after a huge moment for Spain but the whole team deserves credit. Aymeric Laporte and Pau Cubarsi kept another clean sheet as they prevented Ronaldo from scoring again. This means the Spaniards are still yet to concede a goal at this year's tournament, showcasing their brilliant defensive unit.

Lamine Yamal caused Portugal problems even though he was not at his absolute best. Especially after Mendes was replaced in the second half, Spain's 18-year-old grew into the match and looked like Spain's biggest threat.

As Ronaldo says goodbye to a lifelong dream, today paves the way for the next generation, and Lamine Yamal is undoubtedly the face of it. La Roja won the European Championships just two years ago and are now looking like a real force to win the biggest prize in football along with it.

Spain's win sees them advance to the quarter-finals where they will face the winners of USA vs Belgium. Luis de la Fuente's side will definitely be the favourites heading into this match, as they look ahead to a potential semi-final against France or Morroco.

The Spaniards are beginning to pick up lots of momentum now and will be a tough test for either USA or Belgium. Their opponents will be decided later tonight but La Roja will be full of confidence no matter their opponent. 

Earning a place in the last eight makes this Spain's most successful World Cup tournament since they lifted the trophy in 2010. With no goals conceded and confidence now flowing, they will be hoping to replicate their achievement 16 years ago in South Africa. They will be confident of doing so and now look like a real threat, showing their attacking quality, composure on the ball, and defensive resilience to grind out matches.