Cameraman Molly Armstrong:, external USA fans all over this town. Jason Mohammad caught up with them in Salvador for BBC Sport.

Image source, MOLLY ARMSTRONG

But Lionel Messi is not the only threat in the Argentina team, according to Switzerland's Admir Mehmedi.

"With all due respect for his qualities and class, I think too much is talked about just Messi," said the 23-year-old striker.

"He is exceptional, no question, but that is not all, he has very good players around him. We will not neglect the preparation nor in the game itself."

When Argentina take to the field to play Switzerland, Lionel Messi will seek to become the tournament's top scorer. He currently has four goals - one off the lead - and, ominously for the Swiss, is rested after being withdrawn on 63 minutes in his side's win over Nigeria.

• Messi is the second Argentina player to score in all three group games after Orestes Omar Corbatta in 1958.

• All four of his goals in the tournament have come courtesy of his left foot.

• The Barcelona star has dribbled into the area 16 times in three games.

• Over 12.5 million tweets have been sent about Messi since the tournament started.

Argentina have yet to score a headed goal at this World Cup, while 67% of their strikes have come from the left.

Belgium pose a danger from almost everywhere, scoring from the left and right, and with the head.

Switzerland are at their most dangerous down the left (scoring 71% of their goals from that side), while the USA's goals are evenly scattered (one from the head, one from the left and one from the right).

Image source, Getty Images

It will come as no surprise to learn that most teams have scored from inside the penalty box at this World Cup.

All of Belgium's goals have come from within the area, while half of Argentina's goals have been scored inside the box. Switzerland? 71%. USA? 75%.

Roy Keane is relishing the challenge of combining the Premier League with international football after being confirmed as Aston Villa's new assistant manager.

The 42-year-old, who is also number two to Republic of Ireland boss Martin O'Neill, will work alongside Paul Lambert as the pair attempt to revive Villa's fortunes after a difficult 2013-14 campaign.

Keane said: "I am delighted to be joining Aston Villa and I look forward to what promises to be an exciting challenge."

Image source, Getty Images

USA will be hoping to go one better than they managed in 1994, when they also made it through to the last 16 of the World Cup.

On that occasion they were knocked out on home soil 1-0 by eventual champions Brazil.

Not the most memorable of matches, one image remains from that game - the moment Brazil left-back Leonardo was sent off for thrusting his arm at midfielder Tab Ramos.

Ramos, who was playing for Spanish club Real Betis at the time, suffered a skull fracture and had to go to hospital.

"I got from him all anybody could hope for," said Leonardo, who visited Ramos at the Stanford University Medical Center. "He not only accepted my apology, he wished me luck in my career."

Aston Villa manager Paul Lambert expects Roy Keane to be a "great asset" after it was announced the former Manchester United midfielder would become his assistant.

"As a player, Roy was one of the most accomplished in the history of the Barclays Premier League," says Lambert. "Roy has brought that experience into coaching and management. The players will love working with him."

Keane's move to Villa Park will not see him step down as assistant manager with Republic of Ireland.

Send your views on how tonight's matches may go to #bbcworldcup.

Rob Moore:, external Argentina to win in 90 minutes and Penalty's in the Belgium v USA game with USA going through.

That's the same prediction as Mark Lawrenson Rob. Penalty shootout drama again? Surely not.

If you want to know when to take a comfort break, or make a brew, during Argentina's match with Switzerland without missing a goal, then we can (perhaps) help.

Argentina have more often than not scored in the first 15 minutes of this tournament, while they haven't yet found the net between the 16th and 30th minute. Although, that might change because Switzerland have conceded 50% of their goals between the 16th and 30th minute!

Switzerland, on the other hand, have scored 43% of their goals in the final quarter. We hope that helps.

Barcelona sporting director Andoni Zubizarreta praises Luis Suarez for publicly apologising for his bite on Italy's Giorgio Chiellini.

Image source, Reuters

Suarez is believed to be the Catalan club's number one target for the summer and Zubizarreta says the Liverpool player was "humble enough to admit an error".

The club's latest signing - Ivan Rakitic - says Suarez's quality is "unquestionable", adding the Uruguayan "has the necessary quality to play for Barca".

Send us your views on Adam Lallana's move from Southampton to Liverpool for £25m.

Mark Jackson:, external Lallana/Shaw are over priced but Liverpool and Man Utd are paying for the quota of filling Englishness, thus adding 60% to their value.

Kathik:, external Lallana is not overpriced. Effectively an £18m transfer. Shrewd piece of business by Bournemouth to include a sell on clause.

Tweet #bbcworldcup, text 81111 or comment on the BBC Sport Facebook page., external

Martin Keown
BBC Sport pundit in Brazil

"The Argentine public love Diego Maradona in a way that they don't love Lionel Messi because he delivered them the World Cup.

"Messi has to do that. It's even harder now to run through a team like he does. Maradona and Messi both dribble through teams, Messi is the best dribbler we've ever seen. I expect Argentina to beat the Swiss, they've not played brilliantly well but they should still win. They should go on and reach the final stages."

Image source, Getty Images

Argentina forward Lionel Messi has scored 10 times in his past eight appearances for the country.

He is currently one of a group of players second in the race to become top goal scorer for the tournament, with Colombia's James Rodriguez one clear on five.

The only previous World Cup meeting between Argentina and Switzerland was in 1966, when the South Americans won 2-0.

Today's Question of Sport teaser from @QuestionofSport, external is: "Which five countries have conceded an own goal at this year's World Cup so far?"

We will reveal the answers later this afternoon. Stay tuned.

Argentina's round of 16 meeting with Switzerland will see two of the tournament's most timid teams in the tackle go head-to-head.

Alejandro Sabella's Argentina have committed just 22 fouls in three games and only the South American side and Spain on 28 have fewer than Switzerland - who have fouled on 38 occasions.

Costa Rica are still the naughtiest team in the competition with 81 offences.

And so to day 20 where we will learn the full line-up for the quarter-finals of the 2014 World Cup.

BBC Sport pundit Mark Lawrenson is predicting drama and a Belgium penalty shootout win over USA but he expects Argentina to wrap up a routine 2-0 win over Switzerland.

What do you fancy? Tweet us on #bbcworldcup or text 81111.

Image source, Getty Images

Germany defender Per Mertesacker is blunt in his analysis of his side's progress in the World Cup round of 16.

Joachim Loew's side needed extra-time to eventually seal a 2-1 win over Algeria with an easier passage expected.

"Would you rather we played beautiful football but got knocked out?" said the Arsenal centre-half. "Do you think just Mickey Mouse teams are in the last 16? All that matters is we're in the quarter-finals."

Outgoing Greece manager Fernando Santos has angered sections of support after criticising his players' attitudes following their exit in Brazil.

Greece lost on penalties to Costa Rica in the round of 16, prompting Santos to say his players were "more interested in being remembered as the man to score a historic goal for Greece."

"He is blaming the players for the elimination. It's a shame he did not use the talented young players at his disposal instead of being stuck in his ways," tweeted Panathinaikos president Giannis Alafouzos.

Republic of Ireland assistant manager Roy Keane has agreed to take up the same role at Aston Villa.

The 42-year-old will be number two to Paul Lambert and will continue with his Eire duties after manager Marti O'Neill gave the move his blessing.