Hearts edged four points clear of Celtic in this endlessly epic Scottish Premiership title race after drawing at Motherwell - but missed the chance to put maximum pressure on the defending champions before Sunday's Old Firm derby.

Derek McInnes' side managed to come from behind to earn points for the fifth game in a row when Lawrence Shankland cancelled out Stephen Kingsley's own goal.

But despite a second-half surge, Hearts could not find a winner amid dramatic scenes that included a Motherwell disallowed goal, injuries to key players and a controversial decision not to award Hearts a penalty.

Still, they know that victory in their penultimate game against Falkirk at Tynecastle on Wednesday means they would - at worst - go to Celtic Park on Saturday needing to avoid defeat to win a first league title since 1960.

A visit to Fir Park is one of the toughest tests in Scottish football this season, and Hearts initially looked cautious against fourth-place Motherwell despite Shankland's early goal-bound shot being brilliantly blocked by Stephen O'Donnell.

Instead it was Motherwell who took a grip of the game when an incisive move opened space for Emmanuel Longelo to cross and a stranded Kingsley could only divert the ball into his own net.

Hearts, though, have shown character throughout this unlikely title tilt, coming from behind to win their last three games.

Kingsley made up for his earlier lapse by finding Michael Steinwender at the back post, and the defender's wonderful strike was parried to Shankland, who hauled his team level with a composed finish.

From there a frantic second half unfolded as Hearts lost both Marc Leonard and Craig Halkett to Achilles injuries, but they nevertheless pressed on in search of a winner.

They thought they had the chance to grab it from the penalty spot when Tawanda Maswanhise appeared to stand on Alexandros Kyziridis' foot when Hearts took a short corner and referee Steven McLean was called to the monitor.

However the referee surprised Fir Park by sticking with his original decision of no foul.

Kyziridis then headed wide from a fantastic position, and although both sides continued to attack, the Greek winger's chance was the best opportunity to win the game.

While the draw gives Celtic a chance to narrow the gap to one point on Sunday when they host Rangers, it keeps Hearts' chance of winning a first title for 66 years in their own hands with two games to play.

When pursuing a historic league title against the odds, any dropped points might feel like a blow.

But given Hearts' patchy recent away record - just one win in their last five - and Motherwell's strong home form amid a charge for European football, this could be a valuable point that still applies pressure to Celtic.

Derek McInnes would prefer that his side did not keep falling behind, but what cannot be questioned is their mentality and ability to respond to setbacks because they have taken more points from losing positions than any other team in the league.

Hearts also have players like Shankland who step up in big moments.

The big talking point will be the decision by referee McLean to decline the chance to change his call not to award a penalty for the touch on Kyziridis.

Replays showed Maswanhise stood on the winger's foot, albeit without a huge amount of contact. As the referee made his way over to the monitor, most would have expected the usual television signal and a point to the spot.

There was almost a stunned silence when he did not. If Hearts do not win the title, it will be a moment which is brought up time and again and McInnes was fuming after the match.

Nevertheless, it is over to Celtic to respond now before they face their own examination away to Motherwell on Wednesday, at the same time as Hearts host sixth-place Falkirk.

The major negative was key midfielder Leonard and totemic defender Halkett both damaging their Achilles, which has ended their participation in this epic title race.

Only Falkirk have won at Fir Park in the league, and Motherwell's defensive record at home is the best in the division, with just nine conceded before this game.

But the absence of centre-back Paul McGinn due to injury and midfielder Lukas Fadinger for personal reasons tapered Motherwell's vibrancy despite a bright start.

In the second half, they lacked their usual composure to play out from the back as Hearts kept coming, although they still threatened on the break in bursts. McGinn and Fadinger are key components of that.

Jens Berthel Askou's side have been magnificent all season but have a four-point lead to defend to Hibernian with two games left in the race for guaranteed European football and need to finish the job.

They are strong favourites to do so, but a run of one win in their last eight games is a slight concern with Celtic and Hibs left to face.

Motherwell manager Jens Berthel Askou: "Our performance was outstanding. I thought we took control in the beginning. We drove the tempo, took initiative, and we were brave.

"We defended very bravely and strongly in the box besides their goal in the first half, so that was one of those moments we should have done better.

"We had the highest attendance here for more than 20 years and we hope for a huge night on Wednesday. I don't think the final chapter has been written."

Hearts head coach Derek McInnes: "Motherwell deserve all the plaudits they get. In saying that, I don't think they had many opportunities.

"They get their goal and we are disappointed as we should defend it better. We responded well and I thought we were the better team and Lawrence got his goal.

"The biggest thing about my team is their desire to win. Despite obvious injuries and setbacks, we are patched together, we come though with plenty of credit. I think you can see why my team are top of the league."

Motherwell host Celtic at Fir Park on Wednesday (20:00 BST) while Hearts defend their unbeaten home record against Falkirk at the same time.

Live coverage of both matches will be on BBC Sounds and the BBC Sport website and app.