Ross County midfielder Iain Vigurs had just cancelled out Anthony Stokes' early close-range opener when Celtic forward Tony Watt finished off Dylan McGeouch's driven pass from six yards but assistant referee Dougie Potter raised his flag. Television replays showed Watt was onside in the Clydesdale Bank Premier League contest which ended 1-1.
Mjallby was also disappointed his side failed to mark Vigurs, who finished into the top corner from 20 yards after being teed up by Richard Brittain's free-kick, and the Swede said: "We played a good first half and it was very annoying to concede a goal late again in the first half and then we should have had a goal allowed."
He added: "It wasn't offside and goals are always going to change games. I have seen it on television and it clearly wasn't offside. It would have been nice to go in at half-time with a lead.
"It was more annoying to concede a late goal in the first half because we were playing well. We lost a goal out of nothing although, overall, we defended much better and kept our shape.
"The second half wasn't that great, we didn't create that much and went a bit too deep because they had the wind behind them."
Celtic played a 4-3-3 formation and had some first-half success in getting behind County down the sides. But a strong wind exacerbated the problems caused by the barren Global Energy Stadium pitch.
"It is hard to play football on that pitch," Mjallby said. "It was dreadful. We had to go a bit more direct and that didn't suit us. It was more of a physical battle although a draw was a fair result.
"The pitch is equal for both teams but the way we play football it doesn't suit. It is not acceptable to have a pitch like this and it shouldn't be this way although I am not a groundsman.
"It is hard for me to put the blame on anyone but it is not good for the 22 players out there. It is bobbly and there is no grass but it was quite soft and it was not dangerous."
- Sports & Recreation
- Anthony Stokes