Argentina sets sights on Copa semis, with or without Messi

World champions Argentina look to book their place in the last four of the Copa America when they open the knockout stage of the competition against Ecuador at NRG Stadium on Thursday.

The Argentines, defending Copa champions and title favourites, enjoyed wins over Canada, Chile and Peru in the group stage where the solidity of Lionel Scaloni's side was evident throughout.

Confident at the back, well organised in midfield and with a constant threat down the flanks and in attack, Argentina still had to work hard for the points against Canada and Chile earning the opportunity to rest their starters for the 2-0 win over Peru on Saturday.

There remains a doubt over the fitness of Lionel Messi however, who sat out the win in Miami as he nursed a sore right hamstring.

Scaloni said they will assess Messi's condition after training on Wednesday evening and should the eight-times Ballon d'Or winner not be able to start, there could be an opportunity to see strikers Lautaro Martinez and Julian Alvarez operate as a pair.

Although he started on the bench in the first two games, Lautaro is the tournament's top scorer so far with four goals in three appearances.

Curiously, the most recent time that Inter Milan's Lautaro and Manchester City's Alvarez started together was against Ecuador in a pre-tournament friendly on June 9th which the 'Albiceleste' won 1-0.

"They've worked well and it's an option. But we will see how everyone is today, especially Leo, and we will see," said Scaloni.

Ecuador qualified for the quarter-finals ahead of Mexico and Jamaica but had suffered a defeat to Venezuela in their opening group B game.

Argentina have not lost to Ecuador since a World Cup qualifier in 2015 and have never been beaten by them in a Copa America clash.

But Scaloni is wary of reading too much into the head-to-head record.

"I don't believe in statistics, they are there to be broken. Let's hope not. Ecuador is a well-trained team, they have good players and a good coach . It is one of the good teams in the Copa America. It has a real chance of being able to fight for the Copa America. There are no games that are the same, even though we played recently," he said.

Ecuador's veteran striker and captain Enner Valencia, the country's all-time top scorer with 41 goals, certainly believes an upset is possible.

"They have a lot of experience, they've been working together for a long time. They are the best players in the world but we have a young squad but with a lot of personality, respecting our opponents but wanting to win," he said. 

Ecuador's best finish in a Copa America is fourth place, achieved in 1993 and 1959.

Friday sees surprise quarter-finalists Canada, who finished above Chile and Peru in Group A, take on Venezuela, who impressed with three wins from three to top Group B.

Colombia, who topped Group D ahead of Brazil, face Panama on Saturday in Arizona while the most mouth-watering clash in the last eight sees Marcelo Bielsa's Uruguay take on Brazil in Las Vegas.