There was little else he could do as Arsenal came perilously close to being swept away by a tide of some of the most sublime passing and movement fans are likely to ever see.
Runaround: Barcelona's Xavi holds off Arsenal's Neves Denilson
As Walcott admitted, you have to hold your hands up and take what you can from the kind of show Barcelona put on in the opening 45 minutes.
'As a young player growing up and still learning about the game, it was a fantastic experience just to watch some world-class players,' said the Gunners and England winger.
'It was fantastic, it was like someone was holding them with a PlayStation 3 game controller, controlling them all the time.'
If the footballing gods did choose.to take time out for a spot of console football, doubtless there would be a celestial battle over who got to be the Catalan side.
Even Pep Guardiola, having guided his side to an historic Treble last season, conceded that he has never seen a better half from his side since he took charge two years ago.
Guardiola, a hugely-gifted midfielder in his day, should be proud of the wonderful display from his players. But the likeable and modest coach should also step up and take a bow. Performances such as those at the Emirates on Wednesday night do not come without meticulous planning.
Inexperienced though he may be compared to Arsene Wenger, Guardiola's tactics showed you are never too old to be taught a thing or too.
Yet Guardiola is blessed with a team brimming with awesome technical ability and in that first period they enjoyed over 70 per cent of possession, a staggering figure considering the opposition.
Meticulous: Barcelona manager Pep Guardiola
And delving into the statistics of individual players sheds even more light on why they were so dominant.
Seven Barcelona players completed over 20 passes before the break, man-of-the-match Xavi Hernandez topping the list with an incredible 58. Compare that to Arsenal's best performer, Cesc Fabregas who managed just 19 passes, and the reasons behind Barca's superiority become apparent.
But that is only half of the story. That Barca are supreme when keeping the ball is no great secret. But their capacity to regain possession is another vital aspect of their play. From the off, Barcelona were in Arsenal's faces, generally winning the ball back within two or three passes by their opponents. In possession, Arsenal are perhaps the only team on the planet who can normally match Barca stride for stride, so the strategy of ensuring their opponents saw as little of the ball as possible formed the foundation of the Spanish champions success.
The credit for that tactic lies squarely with Guardiola. Much was made about this game being the greatest expression of 4-3-3 that anyone was ever likely to witness.
The only problem was that Guardiola opted to ditch that approach in favour of a formation which, for large periods, was more like 4-2-4.
The upshot was that Guardiola's side operated with a high defensive line, their attacking quartet being the first line of defence. The tactic allowed Barca to impose their passing game on their opponents while Arsenal's customary style of play was stifled almost to the point of suffocation.
Arsenal were denied width and, with Nicklas Bendtner preferring to stay in a central role rather than run the channels, there was no opportunity to exploit the space behind Barca's full back who spent the majority of the opening period in Arsenal's half.
Guardiola's planning married the talent of his players and meant that, but for the heroics of keeper Manuel Almunia, Barca could have been five goals to the good within 15 minutes. Indeed, at times the game resembled an exhibition match, Harlem Globetrotters stuff.
And if it had not been for a spirited comeback, when Barca began to run out of steam, Arsenal's participation in the Champions League could have been over before the second leg.
Instead, at 2-2 they have a chance to complete a rescue mission on Tuesday at the Nou Camp. That can only be achieved if Wenger has learned f rom this week' s masterclass.
But if the Spaniards can produce a performance anywhere near as impressive as that in the first half at the Emirates, then it surely will culminate in a glut of goals.
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