A resilient United, bottom of the table, looked to have earned a point as the game went into the last ten minutes with the two sides locked in stalemate.
But the Bermudan midfielder dramatically found the net just three minutes after manager Jay Bradford introduced her to the action.
Coventry couldn’t find a response in the dying minutes, as Lionesses claimed a second win of the New Year to stay seven points behind league leaders Liverpool with a game in hand.
United started brightly when the ball fell kindly for Freya Thomas inside the area but Lionesses goalkeeper Shae Yanez made a smart save.
Striker Katie Wilkinson, who scored the last time Coventry picked up a point in the league, also looked lively but couldn’t force Yanez into action when she dragged her shot wide.
The visitors' best opening in the first half came when Carly Girasoli narrowly headed Mollie Rouse’s header just over Olivia Clark’s crossbar.
After the break, Clark did have to react to an opportunity, finger-tipping Lucy Fitzgerald’s looping cross behind for a corner before the Lionesses began to turn up the pressure.
It looked like Coventry had ridden the storm as the full-time whistle approached but that was until Thompson’s late show from the bench as she snatched a potentially vital win.
The next shot on target came from Coventry only a minute later, Olivia Fergusson’s diving header forcing Kitching into a smart save to prevent an immediate equaliser.
Sweetman-Kirk slotted home after excellent work from substitute Mia Enderby and Coventry looked out on their feet.
She made Coventry suffer even more minutes later. Again, Enderby started it as her shot was parried by Thomas, and Sweetman-Kirk pounced on the scraps to fire home.
Mollie Green’s free-kick, that appeared to be a cross, which sailed over Kitching’s head, was a consolation for Coventry, but it was too little too late.
United are back in action at BPA on Sunday 23rd and face London City Lionesses. KO 2pm.
The spoils were shared in Coventry’s final match of 2021, at the Butts Park Arena.
Clinton Lancaster’s side went in front when a great free-kick from Emma Beckett put the Hornets a goal to the good.
Coventry went a player down early in the second half, as Grace Riglar was sent off for a second bookable offence.
With a little under 20 minutes to go, United found an equaliser. Wilkinson’s first touch to set it up was great and she then fired a strike into the back of the net.
Coventry had a chance to turn the game completely around, but they were thwarted by Ferguson. A pass was weighted well into the path of Hardy, but she couldn’t beat the Watford keeper.
Lancaster put on some fresh legs up top in the search for a winner, but 1-1 is how it finished.
TEAM: Thomas, Johnson, Riglar, Green, Mann, Orthoxodou (Hartley 61’), Morris, Toussaint, Hardy, Fergusson, Wilkinson (C)
Subs not used: Clark, Chandler, Crackle, McGrother
Goal: Wilkinson (74’)
Red Card: Riglar (51’)
Williams last minute strike sends Spurs Women into last eight of Conti Cup. Williams came off the bench on the hour and was there when it mattered again, this time heading home from Josie Green's cross for 3-2 with only two minutes remaining.
It didn't look that way at half-time after spurs dominated the first half and led 2-0 thanks to goals from Esther Morgan and Angela Addison. However, Coventry, who came into the game with successive wins after a tough campaign so far, pulled a goal back through Destiney Toussaint three minutes into the second half and equalised through Rio Hardy's piledriver on 77. It could have gone either way at that point, but Williams delivered the blow.
The quarter-finals - yet to be drawn - will take place in January.
After a open battle in the first 45 minutes, Katie Wilkinson’s penalty was the difference. However after the break United United would add three further goals in the and were fully deserving of their win.
Wilkinson doubled her tally, while Katy Morris and Rio Hardy also got on the scoresheet.
United progress to the next round
United suffer defeat in this second league match in the FA Women's Continental Cup. Coventry took the lead in this match via Fergusson but Charlton came back with three goals before the first 45 minutes. United put on a better second half performance but could not find the back on the net..
Coventry walk away from this fixture sharing the points. A solid team performance from Jay Bradfords squad.
A Goal From Rio Hardy looked to be enough to secure all three points for United until Bristol pulled the game back level on the 81st minute via Harrison.
Coventry took all three points in the FA Women's Continental Tyres League Cup opening match.
Goals From Katie Wilkinson, Charlie Estcourt and Olivia Fergusson put the game out of reach for Watford in action packed second half for United