John Souttar was among the substitutes, but Neilson turned to Stephen Kingsley to replace the stricken Sibbick from the bench when the young Englishman was carried off in the 74th minute with what looked like an Achillies or ankle injury after a coming together with Motherwell striker Kevin Van Veen.
“The doc doesn’t think it’s too bad and he should be ok for the cup final,” insisted Neilson. “It looked at the time as if he was in a lot of pain and we were a bit concerned, but it seems to be just a bit of nerve damage that he’ll hopefully get over it quickly.”
Some key players returning from injury did get valuable game time under their belts in Lanarkshire, while others were rested with the cup final against Rangers a week on Saturday at the forefront of Neilson’s mind. Before then, however, the Hampden finalists will meet in a dead-rubber dress rehearsal as the league season draws to a close at Tynecastle on Saturday.
Michael Smith and Cammy Devlin did get 15 minutes near the end of a game at Fir Park that Hearts controlled in the first half, and Andy Halliday played well for 63 minutes before being replaced.
But Sibbick’s injury was a blow on a night when goals from Joe Efford and Ricki Lamie either side of Josh Ginelly’s well-taken equaliser gave Graham Alexander’s side three valuable points to secure their place in Europe next season.
Hearts, of course, secured European football weeks ago, and Neilson’s team selection was clearly made with the cup final in mind 10 days hence.
Barrie McKay was missing from the team sheet altogether, with Ellis Simms, Kingsley and Craig Gordon among those left on the bench.
Ross Stewart made a rare start in goal and the last thing he needed was to be picking the ball out of the net after just two minutes and five seconds.
It may have felt like deja vu for the 27-year-old back-up keeper, who was beaten by Ali Crawford inside the opening minute in his only previous start of the season away to St Johnstone back on February 19.
Stone cold because of a severe lack of match practice, Stewart’s parry to keep out a Connor Shields strike after he raced through on the inside right channel rolled straight into Efford’s path just six yards from goal to give him a tap in and Motherwell an early lead.
It was the only meaningful action Stewart was called into in a first half dominated by Hearts, who looked hungry all over the pitch.
Motherwell had European football at stake, but the cup final places up for grabs for those in maroon seemed to give Hearts a spring in their step.
Ginnelly’s razor-sharp equaliser after nine minutes, collecting a poor headed clearance to zip past the static Motherwell defence and slide the ball past Kelly with composure, was the first of several chances for the visitors.
The Englishman’s pace got him in behind again three minutes later, forcing Liam Kelly into a smart save, and he should have had a penalty when barged over by Lamie.
Liam Boyce and Peter Haring also had decent efforts and Ben Woodburn, deployed just behind Boyce and Ginnelly in a 3-4-3 formation, had the look like a player soon to be out of contract and eager to impress. Halliday, on his return from injury, was also bright in the middle of the pitch.
But by the time he was replaced by Ellis Simms just after the hour, Lamie had already fired Motherwell in front. Haring’s defensive header from Motherwell’s corner was a poor one, falling straight into Lamie’s path in the middle of the goal and ten yards out. The defender’s low shot through a crowd of bodies gave Stewart no chance.
The half-time introduction of Van Veen as an extra striker put Motherwell in the ascendency after the interval and Hearts were unable to wrestle it back in a disjointed second half.
The Dutchman was also involved in the most worrying incident of the night for Hearts, his tangle with Sibbick looking like it may have ended the young defender’s season and cup final chances. Time will tell.
Motherwell (3-4-1-2): Kelly; Donnelly, Ojala (Van Veen 45), Lamie; O’Donnell, Cornelius, Goss (Shaw 69), Carroll; Slattery (Tierney 69); Efford (Mugabi 90), Shields (Nirennold 90). Subs not used: Woolery, Campbell, Connolly, Mahon.
Hearts (3-4-3): Stewart; Moore, Sibbick (Kingsley 74), Cochrane; Atkinson (Smith 74), Haring, Halliday (Simms 63), Mackay-Steven; Ginnelly, Woodburn (Thomas 80), Boyce (Devlin 74) . Subs not used: Gordon, Souttar, McEneff, Tait.
Referee: M MacDermind.