Celtic slumped to a 2-0 defeat at Falkirk on Sunday to ramp up the scrutiny on manager Martin O’Neill after a run of three wins in 10 games. The Scottish champions had the chance to extend their lead at the top of the table to seven points, but never recovered from conceding a third-minute opener to Ethan Ross.

Scott Tanser slammed in a second before half-time and the Bairns even had a third goal ruled out by a VAR review for handball against Jacob Murrell. The majority of Celtic’s struggles this season have come in European competition as they crashed out of the Champions League qualifiers and have lost all three Europa League group matches.

But sloppy defensive errors and a lack of a clear tactical plan is beginning to cost them domestically as well. Rangers could now close to within one point of their Old Firm rivals should they win a game in hand.

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Scottish Premiership roundup: Saints dedicate draw to dismissed Steward

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Simo Valakari dedicated St Johnstone’s battling 2-2 draw at Kilmarnock to the goalkeeper Toby Steward, who was dismissed in the 14th minute (pictured) after misjudging a long ball and handling outside his penalty area. Saints then twice fell behind to Cathal McCarthy and Djenairo Daniels, but equalised both times with goals from Danny Schmidt and Joel Cotterill to capture an unlikely point. The substitute goalkeeper Ross Sinclair, who came on at the expense of Taylor Steven, also made multiple second-half saves to help Saints move up to seventh.

Valakari, the St Johnstone manager, said: “Toby has held his hands up and said: ‘I am sorry, boys, for what I did.’ But our team did it for Toby, the boys did it for Taylor, who I needed to take out straight away.

“We are all here playing for each other. We have got each other’s backs when things happen. That tells me my players are ready to accept any responsibility. Early red card, with Toby that’s my tactical choice. I ask my keeper to play very high, like a sweeper-keeper for those long balls. In those moments, for a year, Toby has been fantastic in clearing the ball, reading the ball. It’s a thin line, a little outside the box, that can happen.”

Alfred Johansson admitted he was left to sweat as Motherwell broke a seven-game winless run with a 1-0 win over St Mirren. Lukas Fadinger rattled home a penalty eight minutes from time to relieve some pressure on the Swede as the Fir Park side climbed into eighth.

Johansson was adamant his team were well worthy of a result, which brought welcome relief to both him and his players. He said: “Even more than relief, I felt good, happy, joy, determination. This group has done really well lately and I think it’s very well deserved to get the victory and have at least four points from these last two games. It’s important to build on it, the most important thing today is that we didn’t give away easy goals or big chances at all." Press Association

Photograph: Andy Buchanan/Shutterstock Editorial

“We’re still in a decent position at this minute,” said a defiant O’Neill. “I keep out the noise at the end of it all. A tough one to take because I know we conceded two goals but we could have scored six or seven dead easily.”

Falkirk had not beaten Celtic since March 2007, but were well worthy of a fourth consecutive victory to move up to fourth in the table. O’Neill recalled Cameron Carter-Vickers to the heart of his defence, but that decision backfired when the American international presented the ball to Ross to slam home the opening goal.

The former Celtic goalkeeper Scott Bain was inspired in the Falkirk goal to deny Haissem Hassan and Camilo Durán, while the Colombian forward also struck a post as the visitors pressed for an equaliser. But Celtic’s leaky defence was exposed once more on 38 minutes when Tanser raced forward from left-back and drilled low into the corner.

O’Neill, 74, twice rode to Celtic’s rescue last season to take interim charge, 20 years after his first spell at the club ended. The Northern Irishman then signed a one-year deal in June.

Yet murmurs of discontent among the club’s fanbase have increased in recent weeks with many now calling for a change. “I’ve managed this team now for about a year, give or take a month or two, and I’ve managed before,” added O’Neill. “We’re still top of the league. We came from a mile behind last year to win the league. A mile behind on two or three occasions as well too.”

On Saturday, Ryan Naderi’s dramatic late strike broke down Aberdeen’s stubborn resistance to earn Rangers a place in the Premier Sports Cup final.

Aberdeen restricted Rangers to one shot on target in a low quality first half, but Derek McInnes’s side picked up the pace after the break. Aberdeen survived relentless pressure at times but in the 83rd minute Naderi redirected a strike from James Penrice into the net for his eighth goal of the season to seal a 1-0 win at Hampden Park.

The 23-year-old Naderi later tried to share the glory, saying: “It feels amazing. I’m happy, of course, happy to be the one who scores the goals, but happy for the team. I think we deserved it. We believed we could score right up until the very end and we did, and I think it’s a deserved win.”

It was another close-range strike from Naderi and he joked about this proficiency from distance. The Germany-born Czechia international said: “I’ve tried to shoot twice today from outside of the box and it didn’t go well. So I went back inside the box. Maybe I should just stick to the easy ones! As I said, I’m just happy how it is right now and I’m going to try to stick to it.”

Rangers will face the winners of Sunday’s semi-final between Hearts and Hibernian in the final.