The visitors, who are bidding to earn promotion from the Scottish Championship, hold a 2-0 advantage ahead of the reverse fixture at Victoria Park.
Match preview
Having ended the Scottish Premiership campaign by collecting just one point from three matches, Ross County could feel fortunate not to have finished bottom of the table.
Nevertheless, conceding three times in successive games was far from ideal ahead of fixtures of this magnitude, and it showed in the first leg at Firhill Stadium.
The dismissal of 16-year-old defender Dylan Smith after just 17 minutes most certainly did not help their cause, but Ross County had already been behind when that red card was dished out.
Aidan Fitzpatrick's stunning early effort was followed by a well-taken volley from Brian Graham before half time, yet the home side were unable to add to their lead after the break.
While there will inevitably be frustration from failing to add to their advantage, Kris Doolan will be delighted to have seized full control of the tie.
Partick have now won five successive matches in the playoffs, beating Queen's Park and Ayr United to set up the tie with Ross County.
With 18 goals being scored during those encounters and Thistle being on a 11-match undefeated streak in total, they will have total confidence that they will see out the job on their travels.
From the perspective of Malky Mackay, Ross County's most recent victories are not that long ago, wins over Livingston and Dundee United being posted in succession on May 6 and May 13.
Nevertheless, three defeats in four outings and nine goals being conceded have occurred since then, and Mackay will know that it will take an inspired performance to keep this tie competitive heading into the closing stages at Firhill.
Ross County Scottish Premiership Playoffs form:
L
Ross County form (all competitions):
W
W
L
D
L
L
Partick Thistle Scottish Premiership Playoffs form:
W
W
W
W
W
Partick Thistle form (all competitions):
D
W
W
W
W
W
Team News
Keith Watson is expected to be drafted into the Ross County starting lineup to take the place of the suspended Smith.
Ben Purrington is also in contention to feature at left wing-back, but forward Simon Murray is among those who may have to be content with a place among the replacements.
Alterations are far less likely to be made to the Partick XI given how they performed during the first leg, Doolan not making a switch until the final 15 minutes.
The same starting lineup has been selected for the last three fixtures, with Doolan able to rest players at certain times due to the manner of their performances.
Ross County possible starting lineup:
Laidlaw; Randall, Baldwin, Watson; Edwards, Tillson, Loturi, Purrington; Dhanda, White, Samuel
Partick Thistle possible starting lineup:
Mitchell; McMillan, Muirhead, Brownlie, Holt; Turner, Docherty; Lawless, Tiffoney, Fitzpatrick; Graham
We say: Ross County 1-1 Partick Thistle (Partick Thistle to win 3-1 on aggregate)
Possessing top-flight status, the feeling is that Ross County are still very much in this tie ahead of having home advantage in their favour. However, all of the momentum is with the visitors, who we expect to do what is required to book their return to the Scottish Premiership.