If there is one thing defenders fear more than anything, it is pace. More often than not a defender may be physically built to contend with strength or power from an opposition attacker.
Yet one thing that defenders, more commonly fullbacks, find the utmost difficult to contain is pace. Be it a pacey striker who plays off the shoulder of the last defender or the rapid winger who torments the opposing full back.
As proved by Theo Walcott, in his 24-minute cameo appearance against Barcelona in the first leg of Arsenal's Champions League knock out match at the Emirates, pace can be destructive.
From the moment he arrived onto the pitch in the 66th minute his pace and sheer presence uplifted the Gunners' performance and fans. When given the ball he consistently threatened and terrorised the Barcelona defence, most notably left back Maxwell, who we unable to handle let alone contain Walcott's blistering pace.
Time and time again Walcott raced past the back line and his pace was clinical, as a pass from Bentner enabled him to beat Victor Valdes, albeit slightly fortuitously. It is this reason alone which has kept Walcott at the forefront of England manager Fabio Capello's mind as he decides who to take with him to South Africa.
Despite the fact he has completed 90 minutes of football only a handful of times this season, he offers something no one else in the England squad can offer; sheer, instant blistering pace.
For all of the technical prowess that the likes of Steven Gerrard, Frank Lampard and Wayne Rooney withhold, international defenders will have the capability to contain such technical abilities. Whereas a change of pace in an instant cannot be easily prevented.
If Walcott's cameo appearance in the Champions League proved anything; it was how much of an integral part he could potentially play for England at the World Cup.
Expectation has been heaped on Walcott's fragile shoulders in abundance since former England manager Sven Goren Eriksson selected him at the tender age of 17 for the 2006 World Cup, yet failed to get on the pitch.
Walcott has been under scrutiny ever since as the England and Arsenal fans alike patiently wait for Walcott to progress and demonstrate he has the ability to fulfil his potential.
Less than a month ago, former England player Chris Waddle criticised Walcott and his performances claiming he has "never seen any difference in Theo Walcott since he was at Southampton and broke into the team at a very young age. I've never seen him develop. He just doesn't understand the game for me–where to be running, when to run inside a full-back, when to just play a one-two."
Perhaps Walcott has used this outburst from a former player, who won 62 caps for England, as ammunition and felt he has a point to prove to critics who feel he is merely a pacey footballer without an end product.
If he has the ability to single handedly tear apart arguably Europe's best team's defence in the space of 24 minutes, he can undoubtedly have the same effect on the international stage. His hat trick against Croatia put him on a pedestal and now has a final few Premier League matches to prove to Capello that he has something unique to offer.
Many have pinned England's hopes of winning the World Cup on Manchester United talisman Wayne Rooney, but perhaps the way to unlock world class defences in key matches could be something as simple as a foot race.