The Scottish Cup reaches the last 16 stage after the previous round delivered one of the tournament’s biggest ever shocks.
Here, BBC Scotland picks out what to look out for in the fifth round, including another potential upset, whether Darvel can repeat their heroics, and some all top-flight ties.
Let’s start with the classic football oxymoron; the likely upset… Caley Thistle were beaten 2-0 at home by Queen’s Park, only to get called back after it turned out their opponents had fielded an ineligible loan player. That reprieve, along with their recent record in West Lothian, has all the makings of a good cup yarn.
However, Livingston are ticking along nicely and it’s Motherwell who look the most vulnerable of top-flight sides, given their wretched form.
The Steelmen have not won a league match since the end of October and have lost three on the spin since overcoming Arbroath at Gayfield in the fourth round of this tournament.
Steven Hammell’s men may be glad to be on the road again since they were booed off after losing to St Johnstone, who have now won more league matches at Fir Park this season (err… two) than the home team has.
Motherwell may have seen off Arbroath without too much fuss but Raith Rovers are now 11 games unbeaten in all competitions after seeing off Dundee on penalties to reach the Challenge Cup final.
Sixth-tier side Darvel were the sensation of the last round as they beat Aberdeen in one of the biggest shocks in the 149-year history of the competition.
The Ayrshire side were rewarded with another home tie against League One Falkirk in the last 16, a game which they will relish.
John McGlynn’s Falkirk will be equally confident, though, as they sit second in the third tier on an unbeaten run of eight games, with seven of those wins.
A team from a small Ayrshire village in the quarter-finals would have been unthinkable at the start of the competition, but it is a distinct possibility.
You can see whether Mick Kennedy’s heroes manage it again at Recreation Park live on BBC Scotland from 19:30 GMT on Monday.
There are two all-Premiership ties to get stuck into. Firstly, Dundee United meet relegation rivals Kilmarnock on Saturday for the second time in a fortnight and the fifth time overall this season, having also played in the League Cup.
Three of the four meetings have taken place at Rugby Park, with Kilmarnock winning two and drawing one of those, but United won the only meeting at Tannadice, 4-0 in November.
The result is unlikely to have a big bearing on the relegation battle, but it could certainly affect the mood around both clubs for the run-in.
Elsewhere, Celtic face the only side to beat them domestically, St Mirren. However, the game is at Celtic Park where the 40-time winners hammered Stephen Robinson’s side 4-0 last time and where they are unbeaten in 42 domestic games.
Most would back Ange Postecoglou’s side to maintain their 100% home record in Scotland this season, but St Mirren were the last side to win at Parkhead two years ago, and every record has to end some time.
Finally, a trio of Championship sides – Partick Thistle, Hamilton Accies, and Inverness CT – will aim to knock out the sides sitting second, third, and fourth in the Premiership in Rangers, Hearts, and Livingston.
League Two Elgin travel to meet second-tier high flyers Ayr United, aiming to reach the quarter-finals for just the second time in their history.
“Knowing [Ayr boss] Lee Bullen I am very sure he won’t underestimate us,” Elgin boss Gavin Price said.
“I’m sure they’re quite happy with the draw, it gives them a good opportunity to progress but it is an opportunity for us also and we have got to grasp that.”
How about the cup holders? Well, Rangers are certainly enjoying life under Michael Beale, who has yet to lose a game since taking over from Giovanni van Bronckhorst in December.
However, that run of 11 wins and one draw has not been enough to put any kind of dent in Celtic’s Premiership lead as the big two steamroller the rest, so the cups look Beale’s best bet for success this term.
Following the early season upheaval of a long injury list and demoralising Champions League defeats, there is a settled back four at Ibrox now and healthy competition for midfield places.
It’s been a streaky season for Partick Thistle, who recovered from a horrible run of five defeats in a row to claw themselves back into the promotion race, only to lose their past two at home to teams at the wrong end of the table. But that’s just the kind of thing that goes on in the twilight zone of the world’s toughest division to predict.
Thistle have not been to Ibrox since 2017 and have not won there since 1981.
They did give Rangers a fright on their last Scottish Cup visit in 2008, when Damon Gray gave them a 1-0 lead midway through the second half, only for Kris Boyd to hit back straight away to earn a replay, which went the way of the team in blue.
Talking of replays, now a thing of the past, did you know Thistle played 11 games on their way to their one and only Scottish Cup triumph in 1921? They played three times against Hibs, Motherwell and Hearts before needing just one go to beat Rangers in the final.
All ties at 15:00 on Saturday unless otherwise stated
Hamilton Academical v Hearts (Friday, 19:45)
Raith Rovers v Motherwell
Livingston v Inverness CT
Dundee United v Kilmarnock
Ayr United v Elgin City
Celtic v St Mirren (Saturday, 17:30)
Rangers v Partick Thistle (Sunday, 16:00)
Darvel v Falkirk (Monday, 19:45)