Dundee United have sacked manager Gordon Chisholm after showdown talks with chairman Eddie Thompson.
And United have already had an approach rejected to talk to Inverness Caledonian Thistle's Craig Brewster.
United chairman Eddie Thompson said: "It is hugely disappointing that it has come to this.
"But it is clear that performance standards and results are not as expected by our supporters or, indeed, by myself."
Chisholm's assistant, Billy Dodds, will take temporary charge until a replacement is found.
Former Sunderland and Hibernian defender Chisholm signed a three-year deal in May after taking over from Ian McCall, for whom he had been assistant.
He steered the club away from relegation and reached the cup final as interim boss last season.
But United won only 10 games out of 38 in Chisholm's 10 months in charge.
They lie ninth in the Scottish Premier League and Thompson had previously said that anything other than a top-six finish was not acceptable.
The final straw came on Saturday, when United squandered a 2-0 lead to exit the cup.
"I do not consider that I have unreasonable expectations for the performance of the club and we are obviously failing to meet these at present," said Thompson.
"Rightly or wrongly, football managers are judged on results and, as a business, we cannot afford to under-perform.
"I would like to thank Gordon for all of his efforts on behalf of the club.
"He has behaved with great dignity during the unrelenting speculation that, as ever, surrounds all clubs in a similar position."
Chisholm, who had vowed not to resign, had requested a meeting with Thompson amid speculation that followed Saturday's Scottish Cup defeat by Aberdeen.
"As far as I'm concerned, I'm still manager, but we have to clear this up. Something has to be said here," Chisholm had told BBC Sport.
"I'm still up for the fight. I have no intention of walking away. I see positive things happening."
United and ArabTRUST associate director Mike Barile had mirrored the views of many fans when he said that it was time for Chisholm to go.
"Gordon is a capable and respected person and has carried out his role with dignity," he said.
"Sometimes, in management, being such a nice guy is perceived as a weakness.
"It is very difficult and perhaps the board have left it a bit late because the last few weeks have been very difficult for everybody.
"It has reached the stage now where the manager has lost the confidence of the supporters."
Thompson has invested some £2.5m since taking over at Tannadice in the summer of 2002.
Since then, he has dismissed Alex Smith, caretaker coach Paul Hegarty, McCall and now Chisholm from the Tannadice hot-seat.
Kilmarnock manager Jim Jefferies had been strongly tipped as the next in line but looks like being persuaded to remain at Rugby Park by an improved contract.