For the second time in three Premier League matches, Bruno Guimaraes has come to Arsenal's rescue.
Having sparked their 2-0 win at Sunderland in September with the crucial first goal, the £75m summer signing came off the bench again to have a pivotal impact against Leeds on Saturday.
This time it was the winner as the Gunners came from behind for a 2-1 success in a testing encounter at Emirates Stadium.
But Ecuador international Piero Hincapie was carried off during the warm-down, raising concern the defender has suffered an injury.
He came on as a late substitute against Daniel Farke's side but completed extra running after the final whistle - a practice most clubs use.
A fifth win in six league games put Mikel Arteta's side level on points with leaders Manchester City, but their title defence has certainly not been without its scares so far.
Following on from their comprehensive 3-0 defeat at Brighton last time out, Arsenal fell behind in a league match for a third time in four league matches - and only a David Raya penalty save stopped them from trailing at Sunderland as well.
For large parts of the game against Leeds, they were nowhere near their best but, after going behind in the 55th minute, Riccardo Calafiori and Guimaraes - on his full home debut - secured an important three points.
"It was a great game of football. Leeds were brilliant for one hour." said Ally McCoist on TNT Sports.
"Mikel Arteta made changes when he needed to and the substitutions gave Arsenal what they needed. That's what champions do. Leeds can hold their heads high."
By getting wins when below par the mark of champions or are there reasons for concern for Arteta and Arsenal?
Guimaraes raises level after Brighton woe
Coming into the season as defending champions, Arsenal were looking to make a statement signing to make their rivals take notice.
They did not bring in the attacker they wanted but Guimaraes looks like he could be that key arrival to help Arteta's men build on their success.
The 28-year-old midfielder is a 'win-now' signing in the peak years of his career.
He responded well to a disappointing performance in the defeat by Brighton, where he made his full league debut.
The Brazilian international has now scored two goals that have helped his side to valuable points and justified the decision to spend big on Guimaraes, even if the Gunners are inundated with top quality options in midfield.
Arteta said: "He wasn't at that level against Brighton, and this is the level for Arsenal. Every week, every game, every minute, every action, you have to be at that level.
"Today was much better. That's what we have to demand, and this is what I demand to myself. I'm going to demand the same with the players, because if we do that, he will raise the standards and we will be a better team."
Guimaraes was the first player to score twice from the bench this season and both goals have been from outside the box.
Madueke gets chance after attacking struggles
Arteta made some big calls when naming his starting XI.
He opted to start with German Kai Havertz up front despite the forward returning early from international duty after picking up a hamstring issue, leaving Viktor Gyokeres on the bench again.
Gyokeres had scored four goals, registering in every match for Sweden, in the last international break, but looks to have work to do to win his manager round.
The 28-year-old has yet to start a Premier League game and in his cameos this season has looked far from the level required as a striker who could fire Arsenal to back-to-back titles.
The forward line did not click against Leeds and, with Havertz looking like he lacked match sharpness, thoughts turned towards whether Arsenal missing out on an elite attacker in the summer would haunt them.
Winger Christos Tzolis, who has shone at times this season following his summer arrival, suffered a hamstring issue with Greece and, with Eberechi Eze out of form, Arteta used Noni Madueke on the left wing.
Madueke was left out of the last England squad due to a lack of minutes with Arsenal but, after "being the best player in training for the last 10 days" according to Arteta, now could be the chance for him to prove his worth.
'The last time we put our shirts on, something was missing'
Arsenal won the league last season in part because of their excellent defence.
The Gunners conceded the fewest goals in the league but have already conceded five in six games.
The partnership of Gabriel Magalhaes and William Saliba is one of the best in the world and Arsenal look to be missing the injured Frenchman's calmness.
Ezri Konsa was brought in from Aston Villa for £55m and, despite his quality, is still getting used to his new surroundings.
Left-back Calafiori, though, has proved integral to Arsenal's attacking threat. His equaliser against Leeds was his first league strike this term but no defender has been involved in more Premier League goals than the Italian (one goal, two assists).
"The last time we put our shirts on, something was missing." added Arteta.
"And we need to be very conscious of that. From being exceptional and being the champions to being extremely average, like in that game, is a really thin line.
"So if you don't want it more than the opponent, you are not able to cope emotionally with certain situations, you're going to suffer.
"And we all suffered and we didn't enjoy that game, but then you have to learn the lesson and we certainly done that.
"We speak about it and you could sense that there was something in those tummies."
Related topics
Latest Arsenal news, analysis and fan views
Ask about Arsenal - what do you want to know?
