OF all the names in today's fifth-round draw, none had to endure a more perilous route there than that of Inverness Caledonian Thistle.

When the dust had settled on a riotous first ever Scottish Cup Highland derby, Terry Butcher's side had been deprived of a third away-day scalp in a remarkable week of victories at Celtic Park and Pittodrie. But managing to counter Ross County's injury-time goal with an equaliser of their own was in some ways an even more remarkable achievement.

While Derek Adams went off into the night wondering where Craig Thomson's officiating team got the two extra minutes from – the last goal was officially timed at 94 minutes 10 seconds, despite only three additional minutes being displayed – Butcher could only praise his side's indefatigability and refusal to accept their fate.

So-called "El Kessocko" will reconvene for the replay a week tomorrow and, judging by this six-goal thriller, it should be quite an occasion. Regardless of the best efforts of their Dingwall rivals, the Inverness road show seems likely to run and run and Billy McKay is one of the main reasons why the club have scored in every game this season.

The Northern Ireland striker's fine left-foot opener, way before all the late drama, was his fourth in his last three games, and he is in the best goalscoring form of his life.

"I'm sure the fans went away happy after seeing six goals and a thrilling game," said McKay. "We're a bit disappointed at letting two leads slip but we can't be too down after the way we came back, the week we've had, and the fact we're still in the cup. A lot of Rangers fans have been praising me on Twitter after scoring at Celtic Park. It got me noticed and it was great to go there and get three points, then do the same at Aberdeen, and stay in the cup after a trip to Dingwall."

With Inverness already in the Scottish Communities League Cup semi-finals, McKay is looking for some silverware to top his previous cup highlight, scoring at Anfield as lowly Northampton knocked Liverpool out of the Carling Cup 4-2 on penalties in 2010.

"That goal would be my best cup memory so far but hopefully we can get to a final and get a better one," he said.

Ross County could take pride in their second-half display but the dominant emotion on Saturday afternoon was regret. Rocco Quinn, whose splendid strike restored parity early in the second half, bemoaned their ability to see out games.

"It has been the story of our season so far," said the former Celtic midfielder. "We have been in front in games and conceded late goals, and it has been really damaging to our season."

A McKay strike which went in off the face of a seemingly offside Richie Foran gave Inverness their second lead of the day, but it was an advantage they scarcely deserved, before a deflected Iain Vigurs shot and a Richard Brittain free-kick from an angle which went in via a ruck of players put Ross County in the driving seat.

But the visitors showed the requisite courage and got their reward as Foran lunged at a Ross Draper knockdown, with the last touch going to substitute Philip Roberts. A replay – for which they have home advantage – means the yearning around Victoria Park to take down their visitors a peg or two endures.

"Caley Thistle have been in the SPL for a few years and they are the big club," Quinn said. "We are just a wee club from Dingwall. But we can appreciate where the fans are coming from, and we are just as desperate to beat Caley Thistle as they are."

When the dust had settled on a riotous first ever Scottish Cup Highland derby, Terry Butcher's side had been deprived of a third away-day scalp in a remarkable week of victories at Celtic Park and Pittodrie. But managing to counter Ross County's injury-time goal with an equaliser of their own was in some ways an even more remarkable achievement.

While Derek Adams went off into the night wondering where Craig Thomson's officiating team got the two extra minutes from – the last goal was officially timed at 94 minutes 10 seconds, despite only three additional minutes being displayed – Butcher could only praise his side's indefatigability and refusal to accept their fate.

So-called "El Kessocko" will reconvene for the replay a week tomorrow and, judging by this six-goal thriller, it should be quite an occasion. Regardless of the best efforts of their Dingwall rivals, the Inverness road show seems likely to run and run and Billy McKay is one of the main reasons why the club have scored in every game this season.

The Northern Ireland striker's fine left-foot opener, way before all the late drama, was his fourth in his last three games, and he is in the best goalscoring form of his life.

"I'm sure the fans went away happy after seeing six goals and a thrilling game," said McKay. "We're a bit disappointed at letting two leads slip but we can't be too down after the way we came back, the week we've had, and the fact we're still in the cup. A lot of Rangers fans have been praising me on Twitter after scoring at Celtic Park. It got me noticed and it was great to go there and get three points, then do the same at Aberdeen, and stay in the cup after a trip to Dingwall."

With Inverness already in the Scottish Communities League Cup semi-finals, McKay is looking for some silverware to top his previous cup highlight, scoring at Anfield as lowly Northampton knocked Liverpool out of the Carling Cup 4-2 on penalties in 2010.

"That goal would be my best cup memory so far but hopefully we can get to a final and get a better one," he said.

Ross County could take pride in their second-half display but the dominant emotion on Saturday afternoon was regret. Rocco Quinn, whose splendid strike restored parity early in the second half, bemoaned their ability to see out games.

"It has been the story of our season so far," said the former Celtic midfielder. "We have been in front in games and conceded late goals, and it has been really damaging to our season."

A McKay strike which went in off the face of a seemingly offside Richie Foran gave Inverness their second lead of the day, but it was an advantage they scarcely deserved, before a deflected Iain Vigurs shot and a Richard Brittain free-kick from an angle which went in via a ruck of players put Ross County in the driving seat.

But the visitors showed the requisite courage and got their reward as Foran lunged at a Ross Draper knockdown, with the last touch going to substitute Philip Roberts. A replay – for which they have home advantage – means the yearning around Victoria Park to take down their visitors a peg or two endures.

"Caley Thistle have been in the SPL for a few years and they are the big club," Quinn said. "We are just a wee club from Dingwall. But we can appreciate where the fans are coming from, and we are just as desperate to beat Caley Thistle as they are."