Arsenal eventually broke Newcastle United down to secure a 2-0 win and leave Eddie Howe’s side bottom of the Premier League without a win.
Howe, in the Magpies dugout for the first time after missing last weekend’s 3-3 draw with Brentford because of Covid, set up a team to try to contain Arsenal and eke out a point.
Saka went off injured and his replacement Gabriel Martinelli scored with his second touch, a wonderful volley from Takehiro Tomiyasu’s clipped pass over the top.
“He wasn’t comfortable. He felt something,” said Gunners boss Mikel Arteta of Saka as they await news of what is wrong with the England international.
Both sides had hit the woodwork in an otherwise uninspiring first half.
Jonjo Shelvey’s long-range drive was tipped onto the bar by the diving Aaron Ramsdale – and Pierre-Emerick Aubameyang hit a sitter off the post from six yards out.
Arsenal remain fifth in the Premier League, while Newcastle are five points adrift of safety with just over a third of the season gone.
Newcastle are on their longest ever winless run from the start of a league season. Only one side has ever stayed up in the Premier League after failing to win their opening 13 games – Derby County in 2000-01.
The Magpies know the further adrift they are on 1 January, when they have a chance to spend some of their Saudi owners’ money, the harder it will be to attract quality players.
Next up for Newcastle are two huge ones – home games against Norwich City and Burnley, the other two teams in the relegation zone. They will have to face the Canaries without captain Jamaal Lascelles and Matt Ritchie, who both picked up their fifth bookings of the season at the Emirates.