Resolute defending saw Second Division side Ayr hold Hibernian to a 0-0 draw at Easter Road and force a Scottish Cup fourth round replay.
Derek Riordan went close to scoring on three occasions: he had the ball in the net after 38 minutes only to be pulled back for offside, helped Liam Miller's second-half volley onto the bar and then had a point-blank effort saved by David Crawford late on as Hibs failed to breach the visitors' defence.
Ayr, who showed an enthusiasm and work rate lacking in their hosts, claimed a deserved draw to heap further misery on Hibs boss Colin Calderwood and could have won it only for substitute Andy Rodgers to be denied by Mark Brown in stoppage time.
A first-half hat-trick from Chris Maguire helped Aberdeen to a 6-0 victory over East Fife.
The Dons, who have been dumped out of the Scottish Cup by lower league sides in the last three seasons, eased into the fifth round with a comfortable win over the Second Division outfit.
Maguire struck three times and Scott Vernon grabbed another in a ruthless first-half performance from the Dons that earned them an unassailable 4-0 lead. Vernon added a fifth after the break and substitute Josh Magennis netted a late sixth as the Pittodrie side, already with a League Cup semi-final to look forward to, booked their place in the next round.
Ross County gave themselves another chance to avenge their Scottish Cup final defeat by Dundee United after holding the defending champions to a 0-0 draw in the fourth round at Tannadice.
The underdogs had the ball in the net as they pressed following a poor first half but Andrew Barrowman's goal was disallowed for a foul on the goalkeeper. United forced them back in the final half hour but they lacked a clinical edge in the absence of the suspended David Goodwillie and County earned a fifth opportunity to beat the Tayside club in cup competitions in two seasons.
Two stoppage time goals gave Inverness a 2-0 win and saw them dump lower-league counterparts Elgin City out of the competition.
The resilient visitors were applauded off by the home fans and their 1,200 travelling supporters after almost forcing a replay against their SPL hosts. Resolute defending kept City in the tie up until the second minute of stoppage time when substitute Dani Sanchez broke the deadlock and top scorer Adam Rooney settled things two minutes later.
Nigel Hasselbaink was the hero as Hamilton finally claimed their first home win of the season as they secured a 2-0 win over ten-man Alloa.
Simon Mensing saw a late penalty saved after Alloa goalkeeper Stephen Robertson had been sent off before Flavio Paixao sealed the win in injury time as the majority of the 1,054 crowd headed home happy for once thanks to the win against the Second Division side.