
Dionisi lost yet another defender, Omar Traore, in the first half but his team defended admirably and held a threat on the break throughout the second half after the teams had exchanged goals in the first 20 minutes.
Luca Kjerrumgaard, recalled upfront, headed his side ahead before Danny Imray smashed in an equaliser in a busy opening to the game.
Imray was a threat and hit the post before the break, but Iker Bravo was orchestrating the Hornets attacks and the visitors enjoyed plenty of pressure.
Traore was replaced by Albert Eames and, despite George Thomason hitting the bar, Watford were comfortable for much of the second half, too.
Othmane Maamma and Bravo had efforts, before Lewis O'Brien got a late header all wrong, but Dionisi's side defended their box bravely and were good value for a decent point on the road.
Watford made an industrious start, Othmane Maamma a threat on the counter-attack as he found Amin Nabizada to force the first save of the game.
Wrexham won a couple of early corners at the other end but it was the Hornets who looked equally as dangerous, Amin Nabizada's dangerous delivery finding its way - via Maamma - to Bravo, who couldn't get the ball out of his feet to shoot.
Wrexham soon created the first meaningful chance of the game, though, as Ollie Rathbone fired over after Federico Ravaglia had punched straight to George Thomason.
Not long after, though, the Hornets hit the front.
Luca Kjerrumgaard after his goal (Image: Alan Cozzi/Watford FC)
Kjerrumgaard, whose selection has raised eyebrows, got in front of his man and nodded Omar Traore's cross beyond Anthony Patterson, the Dane's first goal of the season.
Watford had started in just the combative manner they needed to but, just as they were really settling in, were pegged back.
One move stretched the back four, Mattie Pollock and Jordan Zemura diving in desperately, and Kieffer Moore was played in to square for Imray to smash in an equaliser.
Watford continued to impose themselves nicely but couldn't create a clear chance, Bravo pulling the strings but Maamma and Nabizada crowded out in wide areas.
Just shy of the 40-minute mark, Imray nearly scored a carbon-copy goal as Moore was played into space down the left and squared, but the wing-back hit the post.
Down the other end, more pressure saw Kjerrumgaard get to the byline and square for Bove, who couldn't find a team-mate to shoot before he was robbed of possession.
Albert Eames comes on (Image: Alan Cozzi/Watford FC)
Just before half-time, with Watford already down to four fit senior defenders, Traore went down holding his head and could not continue. Albert Eames stepped up as the Hornets' run of full-back absences worsened.
Imray started the second half dangerously, too, racing in down the right and forcing Ravaglia into an early low save.
Bove and Maamma forced a corner at the other end and Patterson saved low from Bravo as the teams exchanged early efforts.
The Hornets continued to apply themselves well from there, Maamma working a chance for himself as he burst through but denied by a last-ditch challenge.
A number of Hornets subs followed and Martin Payero looked tidy in midfield, though they nearly fell behind on 68 minutes when George Thomason hit the bar from a tight angle.
The Hornets defended a flurry of corners as the clock ticked into the final 10 minutes, defending relatively comfortably.
And with seven minutes remaining, they enjoyed a real let-off as Lewis O'Brien mistimed his connection with a free header from close range.
Watford hearts were in mouths in the final seconds as Wrexham won a free-kick in position A1, but the wall did its job and Dionisi's side can take pleasure from a hard-earned point on the road.
We take a point back to Hertfordshire 🤝 pic.twitter.com/6a9GTfvevG
— Watford Football Club (@WatfordFC) August 22, 2026
Watford XI: Ravaglia; Traore (Eames 44), Pollock, Keben, Zemura; Bove (Kayembe 66), Kyprianou; Nabizada (Vata 66), Bravo, Maamma (Payero 58); Kjerrumgaard (Doumbia 66)
Unused subs: Bachmann, Clarridge, Ramirez-Espain, Adu-Poku
Attendance: 10,582 (1,262 away)