Quique Sanchez Flores enjoyed a happy return to Watford as Arsenal blew a 2-0 lead at Vicarage Road to draw 2-2 on Sunday.
Pierre-Emerick Aubameyang looked to have the Gunners well on course for a comfortable three points when he struck twice in 11 minutes before the break.
However, Sanchez Flores, who was appointed as Hornets' manager for the second time last week, after one point from their opening four games of the season saw Javi Gracia sacked, roused the hosts for an impressive second-half fightback.
Arsenal played a huge part in their own downfall too as they gifted possesion away inside their own box for Tom Cleverley to pull a goal back before David Luiz upended Roberto Pereyra, who slotted home the resulting penalty.
A point sees Arsenal only move level with Manchester United, Tottenham, Chelsea and Leicester behind Liverpool and Manchester City in the early season battle for a top-four finish.
Gunners manager Unai Emery said: "We were up in the first half and we knew that we needed to score the third. They had the capacity to come back with the supporters and that's what happened.
"We couldn't break their pressing in the second half. They are physical, a very strong team. They pushed for our mistakes, they were playing for our mistakes.
"When you are trying to break their lines you can have chances. They won the second half and my summary is it is not a good point."
Watford midfielder Cleverley was also frustrated with a point. He said: "I would have snatched your hand off for 2-2 at half-time but we should have won it in the end.
"Arsenal were a bit tentative and we could smell that a bit. I feel we have had a few penalties go against us so it's time we got one that went our way. We can definitely build on this and go forward."
And the team's fighting spirit certainly pleased the returning Sanchez Flores. "The reaction of the players was the most important thing," he said.
"It's easy to be down when you are losing 2-0 to a team as good as Arsenal. But we never gave up and we tried to keep the energy. In the second half we played really well."
In Sunday's early game, Callum Wilson scored twice as Bournemouth curbed early season optimism over Everton's prospects with a 3-1 win.
The England international took advantage of some sloppy defending from the visitors to head home the opener from close range, but Everton levelled before half-time through Dominic Calvert-Lewin.
The Merseysiders have spent big again this summer in a bid to challenge the established 'top six' for a European place, but will need to improve away from home to do so.
Ryan Fraser's driven free-kick restored Bournemouth's lead 23 minutes from time, via a deflection off Fabian Delph, before Wilson's cool finish to lob international teammate Jordan Pickford made the game safe.
Everton have now picked up just one point from three away games this season after also failing to win at Crystal Palace and Aston Villa.
Bournemouth manager Eddie Howe said: "It was hard work. It was a really hot day and our boys performed superbly. It is huge psychologically because our home form is so important."
Howe's Everton counterpart, Marco Silva, admitted his was frustrated with his side's performance. "We lost the game and we gave some things too easily to our opponent," he said. Our home form is fantastic but to win our away games we have to be more aggressive and more solid so that we do not concede easy goals."