Celtic remain three points behind Scottish Premiership leaders Hearts thanks to Alex Oxlade-Chamberlain's early goal against St Mirren - but are left to rue what might have been.

With half an hour left of the day's fixtures, Martin O'Neill's side were set to go level at the summit, until a late rally from the Tynecastle team left the gap at three.

In a laboured display, Oxlade-Chamberlain's first-half finish proved decisive against an impressive St Mirren side and moved Celtic up to second, at least until Rangers face Falkirk on Sunday.

St Mirren remain in 10th place, but are now just two clear of Kilmarnock, who occupy the relegation play-off spot.

The stakes go up for both sides as the games run down.

Celtic just needed to find another answer to the questions they have faced all season. Convincing or not. It really wasn't but they ultimately did what was required.

The home side started brightly enough and thought they had an early reward when captain Callum McGregor's fierce strike was palmed straight to Oxlade-Chamberlain and he instinctively volleyed home but from an offside position.

Just as St Mirren started to get a foothold, the home side struck.

McGregor fired towards goal again. It was blocked and fell perfectly for Oxlade-Chamberlain and he produced a quality finish across Shamal George for the breakthrough that would eventually settle the contest.

The visitors suffered another blow when George had to be replaced by Ryan Mullen after he bravely cut out Daizen Maeda's cross and was caught by Tomas Cvancara.

The striker, who has struggled to show conviction in front of goal, did just that again after Maeda cut back but his shot was tame in a great position.

A second goal would have brought a degree of comfort to Celtic that never came and rarely looked likely to.

In truth, St Mirren looked the better side for long spells after the interval but the hosts saw it out to secure another crucial win in this title race.

If Celtic retain their title, they look like doing it the hard way.

Wins are paramount. Comfortable ones seemingly elusive but right now, not too many connected with Celtic will care. They remain in the fight. Somehow.

It's arguable whether the outcome was fully deserved as there was always that lurking doubt that something might undo them.

That's often been the case this season. Celtic have been crying out for a striker to consistently bang in goals. In this vital win, that was clear as day again.

Benjamin Nygren has been the only one with a clinical edge all season but Oxlade-Chamberlain showed his quality in this crucial step in the title race.

That said, Celtic remain right in the hunt heading into the split and with more home games than away, they're in a position they would absolutely take right now.

St Mirren took six points from the last six to deliver a massive shot in the arm as they try to battle up the table.

Interim manager Craig McLeish seems to cut a calm figure who brings clarity. This was always a tough challenge but they did perform well, particularly after the break.

However, the outcome leaves them with a big fight ahead. Anything here would have been worth its weight in gold.

They have the chance of another huge Hampden upset against Celtic next weekend in the cup but their fight to remain in the top-flight clearly takes precedence.

A home fixture against bottom side Livingston is next in that fight. One they will focus on capitalising on but they can take plenty of encouragement from this performance and recent results.

Celtic manager Martin O'Neill: "Naturally delighted to win the game, that's the most important thing.

"The energy levels concern me a bit, we didn't seem to have that.

"For long periods in the second half, St Mirren were in control. However, we dug in and defended strongly to keep the clean sheet."

St Mirren interim manager Craig McLeish: "We have to take as many positives as we can.

"Ultimately it's a defeat and we're at the stage of the season where we have to put points on the board any way we can."

These two sides meet again next Sunday (14:00 BST) in a completely different context at Hampden Park in their Scottish Cup semi-final.