Former Huddersfield boss Neil Warnock believes Monday's Sky Bet Championship play-off final against Reading is too close to call.
Warnock, who steered Cardiff clear of relegation trouble after taking charge in October last year, won one of his seven promotions as a manager with Huddersfield in 1995.
The Terriers are bidding for promotion to the top flight for the first time in 45 years - they have never appeared in the Premier League - but Warnock could not be drawn when asked to pick a Wembley winner.
He said: "I think Huddersfield have got a great chance of winning and it would eclipse anything the club has achieved before.
"But somehow Reading, who I don't think have been fantastic, have managed to get results.
"It's a toss of the coin isn't it? The season Huddersfield have had, it's fantastic for Dean Hoyle really, he's Huddersfield through and through, but I honestly don't know which way it will go."
Warnock, who won promotion to the second tier with Huddersfield before quitting in 1995, feels both clubs would be competitive in the Premier League.
"They both have lovely stadiums and would both adapt if they get promoted - a bit like Burton adapted in the Championship this season, it was a big step-up for them.
"Reading are dogged and resilient, but I think Huddersfield will have more flair with (Aaron) Mooy and their wide players.
"I really like their manager David Wagner. I think he's done a brilliant job. We beat them twice this season though and we should have got something at Reading.
"Reading have ground out results. (Yann) Kermorgant is one player I'd pick out as being their danger man.
"It will be close and you just don't know with this one."
