Kai Havertz scored the only goal of the game in the 37th minute.
Oliver Glasner’s side now sits 15th in the Premier League table with a difficult schedule ahead.
Arsenal will face the winner of the second semifinal match between Bayern Munich and PSG on Wednesday.
It only took nine minutes for Viktor Gyokeres to put the Gunners ahead.
The striker won the spotkick after he was brought down inside the 18-yard box.
Bayern are through to the Champions League semi-finals after a dramatic 4-3 victory against Real Madrid at the Allianz Arena, while Arsenal edged Sporting 1-0 on aggregate.
Partey is still on bail and has continued to play for La Liga side Villarreal since leaving Arsenal.
Doku expressed optimism that City could still win the title despite the six points gap between them and Arsenal.
Kai Havertz scored a stoppage-time winner as Arsenal beat Sporting CP 1-0 in their Champions League quarter-final first leg in Lisbon.
The defeat comes days after Arsenal lost 2–0 to Manchester City at Wembley.
