Mikel Arteta said Arsenal must now show the resolve of champions after a shock 1-0 defeat to Everton dented the Gunners bid to land a first Premier League title in 19 years.
Arsenal still lead Manchester City by five points at the top of the table, but blew the chance to extend that advantage as they suffered just a second league defeat of the season.
James Tarkowski headed in the winning goal for the Toffees on the hour mark as Everton made a perfect start to life under new manager Sean Dyche to climb out of the relegation zone.
"This is not going to be a rose pathway," said Arteta of Arsenal's road to the title. "This is going to be tricky and we will have to dig in and play much better than we did today."
Everton came into the game on a run of four league defeats at Goodison for the first time since 1958.
That disastrous form cost Frank Lampard his job and Dyche's appointment got the desired bounce with a first win in 11 games.
"The minimum requirement is maximum effort and we saw that today," said Dyche.
Everton's board again stayed away due to rising tensions between the club's hierarchy and supporters.
Protests were planned for before and after the game for fans to voice their anger at the running of the club.
The Toffees were the only Premier League club to not make any signings in the January transfer window despite their perilous position in the table.
But the home side showed there is still enough talent available to Dyche to dig themselves out of trouble if they can harness the same level of energy and intensity on a more regular basis.
- Goodison 'rocking' -
A first victory since October was no more than Everton deserved and it was two of Dyche's former Burnley players who combined for the only goal of the game on the hour mark as Tarkwoski headed in Dwight McNeil's corner.
"The fans are going to be massive for us. I have been here when it has been rocking. It was rocking today. But we have to give the fans something," added Dyche.
"Of course I'm going to drive home and think what a great start but I'm not naive. We have to keep working and improving."
Keeping Dominic Calvert-Lewin fit will be critical to Everton's survival hopes, but the England international showed his rustiness in front of goal in a second consecutive injury-impacted season.
Amadou Onana's surging run and ball across the face of goal just needed a finishing touch that Calvert-Lewin could not stretch to make.
Moments later Abdoulaye Doucoure, who had been frozen out by Lampard, headed a glorious chance wide when unmarked inside the box.
It took Arsenal half an hour to even threaten Jordan Pickford's goal, but they should have led when Eddie Nketiah fired high and wide with just the goalkeeper to beat.
Conor Coady then had to react quickly to turn Bukayo Saka's volley off the line as the visitors began to find their rhythm.
Arsenal were brighter at the start of the second period and Martin Odegaard will feel he should have hit the target when teed up by Nketiah.
But just as the Gunners were beginning to turn the screw, their luck at the back ran out.
Tarkowski was fundamental to Dyche overachievements in keeping Burnley in the Premier League for six consecutive seasons between 2016 and 2022 and the centre-back rose highest to power home.
Arteta's decision to substitute three of his most consistent performers this season in Gabriel Martinelli, Thomas Partey and Odegaard in the second half will be questioned as Arsenal then lacked the guile to break down the mass ranks of defence from Dyche's men.
"This is the moment I love my players more," added Arteta. "This journey is difficult, challenging, there are big stones we have to overcome and we have to prepare well for Saturday (against Brentford)."