Carlisle United were looking to take a 2-0 lead to Brunton Park, but with the seconds ticking away, Freedman snatched onto a loose ball from a Paul Huntington cross in the box and tucked it away.
But Leeds will have to improve on this performance when they meet for the second leg on Thursday and Freedman's goal could give Leeds the momentum they need to book their place at Wembley.
The Cumbrians came into the game on the back of a poor run of form that saw them miss out on automatic promotion and many 'experts' thought they would struggle in the cauldron of Elland Road.
But they always appeared to be ahead of Leeds, showing more energy, commitment and tactical acumen. Leeds did create chances but found visiting keeper Keiren Westwood in outstanding form.
Jermaine Beckford was back into the starting line-up for the leading scorer's first game after missing the final 4 matches of the league season with an ankle problem.
He had a couple of scoring chances but struggled for match fitness and was replaced by Tresor Kandol just before the hour mark.
The visitors took the game by the scruff of the neck with former Bradford City midfielder Marc Bridge-Wilkinson hitting a shot against the post in the opening minutes, Scott Dobie heading just wide and Danny Graham having an effort punched clear by Casper Ankergren.
Leeds also had their moments with Freedman bringing a good save out of Westwood and the Carlisle keeper pulled off an even better, finger-tip stop to deny a curling shot from Beckford that looked set for the corner.
Carlisle finally broke the deadlock in the 31st minute when Simon Hackney hit a cross into the area which Graham shot towards goal, only for Ankergren to turn it round for a corner.
But Leeds didn't defend the corner well and Hackney smacked a shot that deflected off Graham past the Leeds keeper, who had no chance.
That just fired up the Leeds support even more as they awoke to a great run by Bradley Johnson which set up a chance for skipper Jonathon Douglas but again Westwood did well.
Just as in the first half, Bridge-Wilkinson had a chance in the second when he caught Jonathan Howson in possession but shot too close to Ankergren.
But the midfielder made no mistake a minute later when a cross came in from the wing and he swept it home.
Leeds piled on the pressure and when sub Kandol managed to get a header on target, Westwood again stretched and pushed the ball over the bar.
McAllister sent on Seb Carole but, despite close shaves from Johnson and Douglas, Leeds couldn't find the net.
Then Freedman struck and Elland Road went crazy.