Arsenal manager Mikel Arteta fielded an unchanged line-up from the one that dominated and overcame Leeds United 4-2 last weekend. Meanwhile, Benfica boss Jorge Jesus included former Premier League duo Nicolas Otamendi and Jan Vertonghen in his line-up.
After an uneventful first half, Benfica took the lead in the 55th minute thanks to a well-delivered penalty by Pizzi. Emile Smith Rowe was duly penalised for a handball in his own penalty box, and there were no complaints from Arteta's side.
Arsenal's Bukayo Saka scored the equaliser two minutes later, and this will certainly be a crucial away goal for the Gunners.
Unfortunately, both sides were unable to find the winner in the remaining minutes, and the result of the tie will be determined in Athens, Greece next week.
Here are five talking points from the draw.
#5 Arsenal's lack of penetration
Despite enjoying an overwhelming amount of possession in the first 45 minutes, Arsenal's first shot came only in the 19th minute. They struggled to create goalscoring chances or trouble Benfica's goalkeeper Helton Leite.
The best chance came in the 19th minute when Hector Bellerin delivered a cross only for Saka to miss it and Pierre-Emerick Aubameyang to hit it wide from close range.
With Benfica holding their defensive shape, Arsenal ended the first half with only one more shot than their opponents even though they had close to 60% possession.
#4 Arsenal almost punished for multiple offsides
Otamendi and Vertonghen would have surely told their team everything they knew about Arsenal. The two experienced defenders have played against the Gunners multiple times in their careers. This probably inspired Jesus to set up a defensive team against the Premier League side.
The highly coordinated backline meant that Arsenal's forwards such as Pierre-Emerick Aubameyang and Saka were constantly caught in an offside position, and this significantly restricted the Gunners' attacking prowess.
After Saka put the equalising goal in the back of the net, Benfica's defenders called for the offside flag to be raised.
They claimed the English youngster was in an offside position in the build-up to the goal. Following a seemingly long check by the officials, the goal stood, much to the delight of the Arsenal team.