Barry Robson missed a first-half penalty as the Scottish champions dropped two points against the Danish side who, as fourth seeds in Group E, were thought to be cannon fodder for Celtic, Manchester United and Villarreal.

The Parkhead side's 100% record at home in the last two seasons has overshadowed their record of one draw in 15 group matches away from Glasgow.

But Strachan knows his side have to get that elusive win and at least get something from Villarreal in their next game in a fortnight.

He said: "You never know. I think Rangers got through with seven points one year.

"But we've got to go and try and win a game away from home.

"That was our target before we started and it has become more imperative now.

"So we will see. It's a challenge for us. It's not a problem, it's a challenge.

"And it's imperative that we get something from the game in Villarreal but I'm optimistic."

The home side huffed and puffed against the unfancied Danish club but were awarded a spot-kick in the 29th minute when midfielder Shaun Maloney was tripped by Steve Olfers inside the box.

Robson, however, blasted his shot at the legs of Karim Zaza.

Aalborg defender Michael Beauchamp was sent off with 10 minutes to go for a 'last-man' foul on Georgios Samaras when it appeared that Michael Jakobsen was the culprit but Celtic could not find a way past a determined visiting defence.

Strachan believed his players could have taken all three points but insists Robson will decide himself if he wants to carry on with penalty duties.

He said: "We wasted about half an hour of the game but we made enough chances to win.

"We were below the standards we set in the first half but we had a good start to the second half in terms of crosses and chances.

"But we weren't clinical enough and their keeper didn't really make any outstanding saves.

"Barry was a big performer for us last season and he will do it again," Strachan added.

"We will have a look at the penalties but it depends on how he feels."

Strachan had a veiled swipe at referee Matteo Trefoloni and his assistant Giorgio Niccolai who combined to rule out Scott Brown's second-half goal for offside and send off the wrong man.

Strachan said: "It was onside. And I know for a fact that the guy sent off wasn't the guy who committed the foul so one or two other people didn't have a great night."

Aalborg manager Bruce Rioch claimed he knew immediately Beauchamp had been a victim of mistaken identity.

He said: "It appears to be the case of mistaken identity and straight away I thought it was the wrong player.

"There was some confusion among the officials and Michael is disappointed because he wasn't involved."

The former Scotland captain praised his players but continued to play down their potential to influence the group placings.

"They were fantastic," he said.

"We have had a super evening and we don't even want to know what is coming next.

"We have to play Manchester United next and boy, that is going to be a belter but again we will look forward to it."