Real Madrid have a full-back injury crisis: What we learned from Tuesday's World Cup qualifiers takes a look at some of the lessons we can take from a busy night of international football that saw Spain's long winning run in qualifiers come to an abrupt end

A fascinating programme of World Cup qualifiers threw up some great results. Italy marched on with a 3-1 win over Denmark at home, while Spain could not manage to make it 25 wins in a row against France in Madrid.

Netherlands bounced back from a disappointing performance against Andorra to beat Romania 4-1, Portugal were held by Northern Ireland, and Argentina scraped to victory against Chile.

There are lessons to be learned for fans and coaches alike. And, as ever, is here to assess the critical points.

Real Madrid face full-back crisis

Ben Hayward | Spanish Football Writer

First it was Fabio Coentrao, then Marcelo, now Alvaro Arbeloa: Real Madrid have lost three full-backs to injury in the current international break  - and Jose Mourinho will not be amused.

Coentrao broke down in Portugal's 1-0 defeat to Russia on Friday and faces further tests, while Marcelo was seriously injured in training for Brazil and Arbeloa, who was expected to move across to left-back to cover those two absences, limped off in the 1-1 draw at home to France on Tuesday.

So Sergio Ramos, who scored Spain's only goal against the French, may now be forced to switch to right-back, although Michael Essien is another option, with either Raphael Varane, Nacho or Castilla's Jorge Casado coming in on the left.

Super Mario is a true chameleon

Kris Voakes | Italian Football Writer

Many claim it's not really his role to be an out-and-out target man, but when Mario Balotelli is forced into the position as he was for Italy against Denmark he is more than capable of delivering as a number nine.

After Pablo Daniel Osvaldo's needless red card in the opening minute of the second half, Balotelli was left leading the line by himself with the Azzurri clinging onto a narrow advantage, but he was able to not only perform the role of spoiler but also clinch a vital third goal.

Add that to the excellent first touch which sent in Riccardo Montolivo for the opener and it was a fair old night for Mario on his return to San Siro.

Strikers can be Argentina's ace

Rupert Fryer | South American Football Writer

It was back to the wall stuff for Sabella’s men in the opening 25 minutes in Santiago, but Messi and Higuain quickly made Chile pay for their wastefulness in front of goal with a couple of wonderfully-taken strikes.

One of those saw the Ballon d'Or holder equal Gabriel Batistuta’s record of 12 goals in a calendar year for his country, once again proving that Argentina can rely on him when the chips are down. More importantly, the win over Chile showed that Sabella can count on enough firepower to turn a game around.

There still appears to be some frailties at the back, with Chile finding most of their early joy in wide positions. Ezequiel Garay, however, is fast cementing his place as a first-choice at the heart of the back four and dealt confidently with the majority of the early crosses the hosts threw into penalty area.

Van der Vaart still has a role to play

Stefan Coerts | Dutch Football Writer

The Hamburg midfielder appeared to be nearing the end of his international career after being omitted from the Holland squad for the qualifiers against Turkey and Hungary.

Nevertheless, Louis van Gaal called upon Van der Vaart again for the matches versus Andorra and Romania as Wesley Sneijder was unavailable due to injury, and the 29-year-old did not disappoint the Oranje boss. After netting once on Friday, Van der Vaart was once again vital in Holland’s 4-1 win over Romania on Tuesday with an assist and a goal.

He might no longer be an undisputed starter when everybody’s fit, but the experienced midfielder can still add something to the team when fully focused on the task at hand.

Ronaldo can have an off-night

Stephen Gillett | Portuguese Football Writer

What we, and Northern Ireland's manager Michael O'Neill, learned on Tuesday night is that if you pray for Cristiano Ronaldo to have an 'off-night' - it can occasionally happen.

The Real Madrid star started the game with some uncharacteristically sloppy play and, although his class shone through at times, his 100th cap for Portugal was ultimately a disappointment.

What was striking was the contrast in team ethic between the two sides. Northern Ireland, with Steven Davis and Jonny Evans leading the way, were collectively greater than the sum of their parts, while Portugal - once falling behind - gave the impression they hadn't played with one another before.