Luis Suarez (left) has two goals in this World Cup, with Cristiano Ronaldo on fourBBC coverage
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TEAM NEWS
Uruguay centre-back Jose Gimenez could return to the side after missing the game with Russia with a back injury.
Portugal winger Gelson Martins and left-back Raphael Guerreiro are in contention to play after they returned to full training.
Defensive midfielder William Carvalho is a doubt after he missed a training session on Thursday.
Midfielder Joao Moutinho could come into the side after starting on the bench against Iran.
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Groups and schedule
Everything you need to know about penalty shootouts
'Stop Ronaldo and you stop Portugal'
WILL A FAILURE TO WIN THE GROUP HAUNT PORTUGAL?
Will Portugal live to regret the injury-time goal they conceded against Iran? That 1-1 draw on Monday saw them finish second in Group B to set up a match against Luis Suarez and Uruguay, whereas group winners Spain face an easier-looking tie against hosts Russia.
Two-time winners Uruguay cruised through Group A, winning all three games, scoring five times and not conceding any, with a 3-0 win over Russia securing top spot.
A late goal from Jose Maria Gimenez gave them a 1-0 win over Egypt in their opener before Barcelona striker Suarez scored the only goal to see off Saudi Arabia.
Portugal's Cristiano Ronaldo has scored four times in the tournament, with only England's Harry Kane having scored more (five).
Ronaldo's hat-trick gave them a point in a thrilling 3-3 draw with Spain in their first game, before the Real Madrid forward got the only goal in a 1-0 win over Morocco.
Ricardo Quaresma's superb strike gave them the lead against Iran in their third group game, before Ronaldo missed a penalty.
Iran then gained an injury-time penalty after a handball by Cedric Soares, with the spot-kick given via the video assistant referee, and Karim Ansarifard converted it to drop Portugal from first to second in the group.
VIEW FROM BOTH CAMPS
Uruguay coach Oscar Tabarez: "We need to improve very quickly [from the performance against Russia], because any match in the round of 16 will be extremely difficult.
"For me the holy grail of football is the word 'balance'. When we attack we need to be able to attack, but it doesn't come from an abstract suggestion."
Uruguay defender Sebastian Coates, talking about Portugal's Cristiano Ronaldo, said: "We will mark him with the same respect we mark everyone, despite him being a superstar. You don't prepare a match just looking at one player."
Portugal coach Fernando Santos: "They are a typical South American side.
"It's not just in this World Cup that they have not been conceding goals - it has been like that for the whole of 2018.
"Oscar Tabarez is the longest-serving international manager. That means he has a very strong relationship with his players."
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World Cup 2018: Best goals of the group stageLAWRO'S PREDICTION
This will be a busy evening for the referee, not least with Uruguay's Atletico Madrid centre-halves Diego Godin and Jose Jimenez up against Portugal's Real Madrid striker Cristiano Ronaldo.
Portugal will not change the way they play, which is quite one-dimensional and not particularly inspiring.
Uruguay have not exactly set this tournament alight with their attacking play either, but they are more adventurous and have a few more ideas when they come forward.
Lawro's prediction: 1-0
Lawro's full predictions
Uruguay's Edinson Cavani has scored three World Cup goals, one v Germany in 2010, one v Costa Rica in 2014 and one v Russia in 2018. His team-mate Luis Suarez has seven World Cup goals, three in 2010, two in 2014 (both against England) and two in 2018MATCH FACTS
Head-to-head
- This will be the third encounter between Uruguay and Portugal and their first at the World Cup. They have not faced each other since July 1972, when they drew 1-1 at Rio de Janeiro's Maracana stadium. Portugal are so far unbeaten in their two previous meetings (won one, drew one).
Uruguay
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Since the format of the World Cup changed in 1986 to include a round of 16, Uruguay have been eliminated on three of the four occasions they have reached that stage, losing in 1986, 1990 and 2014, but progressing in 2010 against South Korea.
Uruguay will be looking to win their opening four games at a World Cup for only the second time after 1930, when they won the first ever World Cup.
Uruguay are yet to concede a single goal at the 2018 World Cup, facing just six shots on target in three games - the last South American team not to concede in their first four matches of a World Cup tournament was Brazil in 1986.
All five of Uruguay's goals at the 2018 World Cup have been scored from set-pieces (three from corners, one from a direct free-kick and one from an indirect free-kick). Meanwhile, three of Portugal's last four goals have come from outside the box.
Luis Suarez has scored seven World Cup goals for Uruguay, second only to Oscar Miguez (eight) - Suarez scored twice against South Korea in his only previous World Cup appearance in the round of 16, in 2010.
Portugal
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Penalty shoot-outs excluded, Portugal have lost only one of their last 17 games at major tournaments (won eight, draw eight), a 4-0 defeat against Germany at the 2014 World Cup. However, they have lost their last three games in the World Cup knockout stages (one goal scored, five conceded).
Cristiano Ronaldo has so far failed to score a single goal for Portugal in the knockout stages of the World Cup: 424 minutes, no goals. However, he did score a hat-trick against Spain in his previous game at Sochi's Fisht Stadium.
If he plays, Portugal's Cristiano Ronaldo (37) will equal Bastian Schweinsteiger (38) as the player with the most appearances at World Cups and European Championships.
This is Fernando Santos' fourth major tournament in a row as manager. He has reached the knockout stages on each previous occasion: Euro 2012 quarter-finals & World Cup 2014 round of 16 with Greece; Euro 2016 winners and at least World Cup 2018 round of 16 with Portugal.
Chances of winning the World Cup
Football statisticians Gracenote Sports believe Portugal have a 6% chance of winning the World Cup, while Uruguay's chances are rated at 5%.
Gracenote Sports head of analysis Simon Gleave said: "Uruguay came into the 2018 World Cup as outsiders but their victory against Egypt in the opening match immediately increased their chance to 5%. A less impressive narrow win against Saudi Arabia reduced their chance a little but they go into the knockout phase back on that 5% chance of lifting the World Cup.
"Portugal improved their chance of winning the competition when they drew their opening match against Spain. A win against Morocco after that improved Portugal's probability still further. Portugal, like everyone else playing on Saturday, are one of 11 teams with at least 5% chance of winning the competition."
Source: bbc.com