A member of Canberra's undefeated championship last season, Sydney FC's Emma Kete crushed her former teammates by scoring the winning goal four minutes into stoppage-time to seal a 4-3 win for Sydney.

United has fallen to sixth on the W-League ladder at the midpoint of the season, two points outside the top four.

Canberra coach Jitka Klimkova was unable to hide her disappointment at the last-minute loss, having fallen the same way in United's last match in Japan the week before.

''It's every emotion in me now,'' Klimkova said. ''These two games in a row and it's even harder to take [this time].''

United had fought back from an early 2-0 deficit after Klimkova gave her troops a loud verbal spray when play was stopped midway through the first half for a drinks break due to the heat.

United responded, twice coming back from a deficit and drawing 3-3 in the 83rd minute when new American import Nikki Washington scored from a wide cross that drifted into the top corner of goal.

Klimkova was unwilling to blame the heat or United's hectic travel schedule for their slow start or the last-minute lapse in concentration.

''This game was like crazy game, up and down,'' Klimkova said.

''For the spectators, it was absolutely amazing, but for the coaches, we have to take a lot from that, mainly the concentration at the end. This is what we want to be strong with, but we're just not.''

United had a sluggish start, trailing by two goals after 17 minutes, with Kyah Simon and Sam Kerr doing the early damage.

Fired up by Klimkova's address, Canberra responded when Georgia Yeoman-Dale scored her first W-League goal, United trailing 2-1 at the break.

A shot from Hayley Raso in the opening minutes of the second half stretched the FC goalie Sian McLaren, who managed to push it high, but the speedy 18-year-old eventually got the equaliser in the 58th minute.

Raso arrived at a through ball from Yeoman-Dale faster than the advancing McLaren, slotting it home as the two collided.

Having saved a penalty from Simon in the first half, United keeper Mackenzie Arnold wasn't able to repeat that effort in the second as Simon converted to give Sydney a 3-2 advantage.

Washington's equaliser gave United their chance to win. But with injury time ticking down, Simon struck for Sydney again by breaking through the defensive line and setting up Kete for the winner.

After a physically draining game, United must play Perth Glory on Wednesday.

W-League: SYDNEY FC 4 (Kyah Simon 5', 77' (pen), Sam Kerr 18', Emma Kete 94') CANBERRA UNITED 3 (Georgia Yeoman-Dale 33', Hayley Raso 58', Nikki Washington 83') at Leichhardt Oval, Sydney.