The hosts are struggling to cope from set-pieces as another Morton corner causes consternation in the Annan penalty box.

"On-loan Morgaro Gomis is tormenting the cup holders with his dribbling skills. Delightful to watch," says BBC Scotland's Chick Young.

Dundee hit the post through Nick Ross, the ball bouncing straight back out off the base of the left upright after some good set up play by Greg Stewart. Dumbarton survive.

End-to-end stuff in a bruising opening period at Tannadice. Coll Donaldson fails to convert Sean Dillon's corner for the hosts, before Thistle race downfield and Sean Welsh fires over.

St Johnstone defender Tam Scobbie is unlucky to see his shot thump against the post as the hosts look for a response to losing that early goal.

Denny Johnstone draws a great stop from home goalkeeper Jordan Hart and the following corner is scrambled off the line.

Andy Considine picked up an injury in the warm up, so Mark Reynolds takes his place in the starting line-up. Scott McKenna comes on to the bench for the visitors in Perth.

Here we go!

"The pitch at the Cheaper Insurance Direct stadium is very soggy due to some heavy pre-match rain," says BBC Scotland's Kenny Crawford. "It seems we'll get kicked off all right between Dumbarton and Dundee but the surface will probably cut up pretty quickly."

Ross County manager Jim McIntyre: "We have to be at it right from the first whistle. We are favourites but Celtic were favourites last weekend and see what happened so we will give Linlithgow every respect."   Linlithgow Rose manager David McGlynn: "They are a full time Premiership club who proved how good they are by beating Celic last week so of course it is going to be difficult. But we have a game plan and if we can frustrate them then hopefully we can give a performance our fans can be proud of."

Dundee United lifted the Scottish Cup in 2010 but I'm sure their fans would swap further silverware for Premiership survival this season.

These two were scheduled to meet last Saturday but the Firhill pitch was waterlogged. United have not featured since, while the Jags sneaked a late win over Motherwell on Tuesday.

Unsurprisingly, United are unchanged from their last outing; a 5-1 win over Kilmarnock.

Annan will fancy their chances at home to Morton after toppling Premiership Hamilton in the last round. It was no fluke at Galabank either, with the part-timers from League Two enjoying a wonderful 4-1 victory.

It even made the news in Iraq, as you can see from this nice work from the Get Inspired team.

Dons boss Derek McInnes makes three changes to his starting XI after Wednesday's 2-1 win over Celtic.

"It's partly tactical and partly to freshen things up," he explains on BBC Radio Scotland. "Peter Pawlett and Cammy Smith are champing at the bit to play."

Andrew Considine is the other addition, with Mark Reynolds, Niall McGinn and Craig Storie dropping to the bench.

Annan Athletic: Hart, Breslin, Watson, Gilfillan, McNiff, Sloan, Flynn, McStay, Morton, Todd, Omar. Subs: McColm, Currie, Osadolor, Norman, Jago, Guy, McDonald. 

Morton: Gaston, Pepper, Kilday, O'Ware, Russell, Barr, McKee, Forbes, McCluskey, Johnstone, McManus. Subs: Lamie, Miller, Scullion, Tidser, Samuel, McGowan.

Linlithgow Rose have put in the miles to get to become the first junior side to reach the last 16 Scottish Cup.

They've been up and down the country; Galashiels, Inverness and Wick, before beating Forfar in a replay, and now they're in Dingwall taking on the 2010 finalists.

This is a massive step up for the visitors and Ross County will be in good spirits after last weekend's League Cup semi-final win over Celtic.

Image source, SNS

Ross County: Gary Woods, Fraser, Boyd, Quinn, Reckord, De Vita, Irvine, McShane, Franks, Graham, Schalk. Subs: Fox, Robertson, Gardyne, Boyce, Foster, Murdoch, Martin Woods. 

Linlithgow Rose: Adams, Tyrell, Ruari MacLennan, Leiper, Batty, Batchelor, McKenzie, Thom, Weir, Kelly, Coyne. Subs: Jones, Strickland, McKinven, Kelbie, Gray, Shirra. 

Dundee United: Kawashima, Demel, Dillon, Gunning, Donaldson, Paton, Rankin, Spittal, Dow, Murray, McKay. Substitutes: Zwick, Dixon, Knoyle, Durnan, Fraser, Anier, Sinema-Pongolle

Partick Thistle: Cerny, Miller, Seaborne, Welsh, Booth, Osman, Bannigan, Doolan, Lawless, Frans, Lindsay. Substitutes: Scully, Amoo, Elliott, Nesbitt, Edwards, Fraser, Pogba.

Motherwell: Ripley, Hammell, McManus, Kennedy, Law, Pearson, Lasley, Gomis, Johnson, Cadden, McDonald. Substitutes: Samson, Laing, Ainsworth, Chalmers, Moult, Leitch, Thomas

Inverness Caledonian Thistle: Fon Williams, Raven, Tremarco, Warren, Draper, Devine, Tansey, Danny Williams, Vigurs, Mbuyi-Mutombo, Storey. Substitutes: Esson, Ryan Williams, Roberts, Wedderburn, Polworth, Hughes, Brown.