Sokratis Papastathopoulos and Eddie Nketiah were on target as Arsenal battled for a 2-0 win at League One Portsmouth that booked their place in the FA Cup quarter-finals.
The Gunners survived some nervy moments to take an undeserved lead into the break at a noisy Fratton Park thanks to Sokratis' well-taken goal in first-half injury time.
Nketiah then scored for the third time since returning from a loan spell at Leeds United in January early in a far more comfortable second half to end any hopes of an upset from a game Pompey side.
Arsenal, record 13-time FA Cup winners, struggled in the opening exchanges and saw Lucas Torreira taken from the field on a stretcher after a robust challenge from James Bolton.
Gareth Evans wastefully headed wide from Steve Seddon's delivery after 28 minutes before Gabriel Martinelli was unable to direct Reiss Nelson's fizzed cross home from three yards as Arsenal finally threatened.
The breakthrough arrived against the run of play on the stroke of half-time when Sokratis expertly guided in Nelson's low right-wing ball on the volley.
Portsmouth's game was run five minutes after the break when Nelson's ball to the front post found Nketiah, who smashed in from practically on the goalline despite a heavy first touch.
Bukayo Saka tested Alex Bass, who tipped the full-back's drive over for a corner, as Arsenal controlled the second half at a pace akin to a training exercise.
What does it mean? Gunners still in silverware hunt after European blow
Arsenal limped out of the Europa League with a disappointing 2-1 home reverse to Olympiacos on Thursday and the FA Cup possibly represents their best route back into continental competition next term. Mikel Arteta will insist publicly they can do so via the Premier League, but this remains a very important contingency plan.
Nelson a difference maker
It was far from a textbook performance from the visitors, though Nelson's pace and direct running caused Portsmouth trouble down the left channel. He was the architect for the two goals and would have been for another if Martinelli could have adjusted in time to head home his cross.
Arsenal still susceptible defensively
In the end it was job done for Arsenal, but with some better first-half composure from Portsmouth it may have been a different story. Sokratis scored but had a few uncomfortable moments as a makeshift right-back, while David Luiz and debutant Pablo Mari did not always convince as a centre-back pairing. In fairness, the second half was a much-improved showing as Portsmouth struggled to replicate a spirited opening 45 minutes.
Arsenal return to Premier League action at home to West Ham on Saturday, while Pompey continue their League One title bid at fellow promotion chasers Peterborough United.