Arsenal’’s German defender Per Mertesacker celebrates scoring the opening goal of the English FA Cup

Arsenal got back on track as Per Mertesacker helped the FA Cup holders silence the critics with a 2-0 win over Hull in the third round on Sunday.

Arsene Wenger’s side had come in for more vitriolic abuse after the latest setback in their spluttering campaign at Southampton in midweek, but Mertesacker’s first half opener and an Alexis Sanchez strike in the closing stages erased the bitter taste of that 2-0 defeat.

Mertesacker had shouldered his share of the blame for Arsenal’s fragile defensive displays this season, but the German centre-back produced the perfect response in freezing conditions at the Emirates Stadium.

Sanchez weighed in as well with a fine finish which condemned Hull to more FA Cup misery eight months after Arsenal came from two goals down to beat the Tigers in the final at Wembley.

That victory ended Arsenal’s nine-year trophy drought and was supposed to signal the start of a new era of success for the north Londoners, but instead their campaign has been marred by the same inconsistencies that have plagued them for so long.

In the circumstances, Wenger will have been pleased with a routine win and the return of Theo Walcott, who made his first start since suffering serious knee injury exactly a year ago against Tottenham at the same stage of the Cup.

Walcott, 25, missed Arsenal’s FA Cup final win and England’s World Cup campaign as a result of the injury and had only 51 minutes of first-team action in three substitute appearances since then.

But he lasted for 76 minutes on his return to the line-up and Arsenal’s attack should be stronger if he can stay fit in the second half of the season.

Hull, battling at the wrong end of the Premier League, made their priorities clear with 10 changes from the team which beat Everton on New Year’s Day and it was no surprise to see them struggle to get a foothold in the game.

Arsenal created the first chance when Joel Campbell’s close-range shot was blocked by Hull goalkeeper Steve Harper after the Costa Rica forward’s exchange of passes with Sanchez prised opened the visitors’ defence.

Walcott then picked out Sanchez for a deft chip that dropped onto the roof of the net.

Arsenal’s dominance was rewarded as they took the lead in the 20th minute.

It was a moment of redemption for Mertesacker, who had been criticised for his sloppy defending in the Southampton debacle.

Sanchez swung over a deep corner towards the far post and Mertesacker rose above Hull captain Curtis Davies to head down and past Harper.