Substitute Kerr was brought on in the 77th minute on Friday evening (Saturday AEST) - the fourth consecutive match she's come off the bench in the last quarter - and though she only got a few touches during her 17 minutes, her busy, bustling presence helped give Chelsea some belated impetus in an even contest.
Ultimately, though, it was frustrating for the Australian's fans to see one of the world's great strikers still being handed another short stint in which it's difficult to find any rhythm as Kerr tries to regain full fitness following 21 months out of action with her ACL injury.
In total, Kerr has been on the pitch for 91 minutes in the four matches since her return, scoring just the one goal that she eked out in stoppage time of her first game back against Aston Villa.
Chelsea coach Sonia Bompastor was happy with her contribution, and that of her other substitutes brought on late as Chelsea tried urgently to mark the start of their title defence with a fifth straight win.
Instead, they had to settle for their first dropped points of the campaign, as they now lead the table on 13 points, ahead of United, on 11.
"I wouldn't say it was satisfying, but it's a tough place to come," said the usually mild-mannered Bompastor, who earned a rare booking for complaining about Chelsea not being awarded a free-kick.
"We tried to find the winner in the last 30 minutes, and I think the players that came in did well, they brought energy and opportunities. But 1-1 was maybe a fair result."
United were thankful for a blistering goal from Anna Sandberg as they came from one down to earn their deserved point against the side who've the last six WSL titles.
Chelsea had gone ahead with a beautifully worked opener in the ninth minute when Catarina Macario's inspired back-heel set up Dutchwoman Wieke Kaptein to slot home into the corner.
Swedish defender Sandberg then equalised 11 minutes later, latching onto a ball from Ella Toone and hammering a thunderous first-time finish from outside the box past the world's top keeper Hannah Hampton, her first goal for the club since signing 14 months ago.
