Back in the heat of summer, midway through Theo Walcott’s year of recovery from ruptured cruciate ligaments, he posted a photograph of himself and Alexis Sánchez arms around each other with thumbs up and beaming smiles. The accompanying message as he met Arsenal’s Chilean whiz for the first time oozed a combination of excitement and bravado: “Watch out Premier League me and Alexis will be a deadly force! Speed matters.”

Fast forward six months, to a chilly January evening, and fitness permitted Arsène Wenger to field these two speedsters in tandem for the first time. Considering his length of absence Walcott looked reasonably sharp in terms of his movement. But alongside him Sánchez’s zest was simply extraordinary. No matter he has played at a relentless, chasing pace, haring around the pitch like a hyperactive kid that has eaten too many sweets, for almost the entire season.

Having played every minute of festive football during his first English winter, he would not countenance a breather for this FA Cup echo of last May’s final against Hull City. In training on the eve of this third-round tie the coaching staff were almost imploring him to take it easy. But the only way of playing football that makes sense to Sánchez is at full pelt. Midway through a comfortable first half against a heavily rotated and underwhelming Hull City, he almost tried to tackle his own team-mate, Joel Campbell, such was his desire to get hold of the ball.

Sánchez has played almost 2,400 minutes of football for Arsenal since the start of the season – more than he was granted during the whole of the La Liga campaign with Barcelona last term. He has barely skipped a beat, sitting out only one Premier League game (at Villa Park in September) and one Champions League game (at Galatasaray when Arsenal were already qualified). He did not even get a rest for the Capital One Cup and flew long haul to buzz through three friendlies with Chile.

For opposition defenders, it must feel as if there is a bionic mosquito tormenting them. The game’s most dazzling moments belonged to him, as he frequently stole the limelight with his audacity – half rampaging bull and half flourishing bullfighter all in one package.

Sanchez was foiled on a handful of occasions in his quest for goals but persisted to add to his collection of 16 this season, rifling in a shot on the low-gravity turn. He also engineered the assist for the opener, steering a corner past the first man (a rare sight in these parts) enabling Per Mertesacker to usher the ball in with his head.

A cup run turned out to be exceptionally meaningful for Arsenal last season and, considering the reality of their Premier League position and the quality of Champions League opposition, it is wise for Wenger to tackle the FA Cup with full attention. He fielded a strong line-up with a smattering of useful changes.

In terms of the long-awaited link-up between Walcott and Sánchez there was a hint of what might lie in store, although there is plainly work to do in terms of developing an understanding. Precisely one year after Walcott was carried off this arena gesturing a 2-0 scoreline at visiting Tottenham fans, he moved well on his return but his touch was not yet in the groove.

Completing the attacking trio, the Costa Rican forward Campbell snuck up the pecking order with Lukas Podolski starting afresh at Internazionale. He had some dangerous moments but lacked the finishing power of the German when he had sight of goal.

As for the suggestion that this might be a perfectly timed opportunity for David Ospina to stake his claim in goal after Wojciech Szczesny’s recent blunders the game did not offer many clues as the Colombian was a virtual spectator. Even from Ospina’s vantage point watching Sánchez must have been a pleasure.