It was after an opening 45 in which the Golden Girls played well at Butts Park Arena, and were unlucky not to have found themselves on the scoresheet.
The hosts came out firing following the resumption though, with three quick goals. Strikes from Charlie Estcourt, Katie Wilkinson and Olivia Fergusson ensured it would be Coventry who took all three points in the opening group fixture.
Watford Head Coach Clinton Lancaster opted to make four changes to the side that had impressed in defeat against London City Lionesses at the weekend.
Mia Smith came in for her first start for the club in goal, while the midfield three was also given a refresh, with Emma Beckett, Megan Chandler and Jenna Legg all starting.
After an even first quarter-of-an-hour, it was the Hornets who had the first real chance. A lovely move from Watford resulted in Adekite Fatuga-Dada hitting the far post and the ball staying agonisingly a yard or two from goal.
The Golden Girls were putting a number of teasing balls into the area throughout the opening 45, with opposition keeper Olivia Clark excelling in dealing with them.
It was Smith though who would make the biggest save of the half. Estcourt was through one-on-one but she was superbly denied by the Watford keeper who made herself big.
From the resulting corner the home side went even closer. Rio Hardy’s header came back off the crossbar, with captain for the night Anne Meiwald well positioned to clear it away from danger after.
Both teams would have one more big chance before the interval. A low cross managed to get through to Fergusson at the back post, but she couldn’t keep her shot down.
At the other end, Fatuga-Dada did well in the build-up to set up Flo Fyfe, with the forward then having an effort that went narrowly wide.
Meiwald was involved in the last of the action at the end of the first half, as she almost managed to acrobatically get an attempt past the pile of bodies in the penalty area.
That would be her last impact on the game, with a knock to the defender forcing Watford to re-shuffle the side after the break.
The Hornets started the second half strongly and almost broke the deadlock early on. A brilliant ball in by Fyfe found Rosie Kmita at the back post and Clark came up with a key stop to keep her shot out.
It would be Coventry who would get the opener though, as the hosts found a way through in the 52nd minute. Ryah Vyse did well to charge down the initial attempt, but it would eventually fall to Estcourt, who picked out the bottom right corner to make it 1-0.
They built on that and then doubled their advantage shortly after. Wilkinson got into space in the penalty box and powered an effort across goal, leaving Smith with no chance.
It was a crucial spell that would see Coventry net three times inside 10 minutes. Wilkinson turned provider for the next one, sending Fergusson through one-on-one and she made no mistake.
United’s number 11 then had a chance for a brace having won possession in a dangerous area, but this time Smith got the better of her with a good save.
The home side would then hit the bar for the second time in the match. Ylenia Priest put her head on the line before the ball then cannoned off the crossbar. The rebound fell to Phoebe Warner, however she couldn’t make the most of the opportunity.
There would be a Watford debut in the second half. Summer Roberts was introduced from the bench and the Development Team player impressed after coming on.
The score remained at 3-0 though, as Coventry took all three points in the opening group stage game.