Scotland manager Gordon Strachan admitted that Gibraltar made his life a misery during his side's 6-1 win over the Group D minnows at Hampden on Sunday.

The Scots had taken the lead through a soft Shaun Maloney penalty in the 18th minute, but were left shocked when policeman Lee Casciaro equalised just over a minute later to claim his nation's first competitive goal.

Strachan's side recovered to restore their advantage through a Steven Fletcher header in the 29th minute, before Maloney added a third with another penalty five minutes later and Steven Naismith made it 4-1 in the 39th minute.

Fletcher headed home his second in the 77th minute before his 90th-minute strike completed his hat-trick -- the first by a Scotland player since Colin Stein put four past Cyprus in 1969.

However, Strachan said he was left scratching his head at times during the win as his side allowed Gibraltar chances.

"All the credit should go to Gibraltar today. They made my life a misery for periods of that game," Strachan said.

"We had a practice game yesterday on this surface and it was the best I've seen from an international team moving the ball around so well.

"I expected the same thing today. There was some nice stuff at times, but some stuff that wasn't so great on the eye.

"We fell asleep. We took it for granted that Gibraltar weren't going to score. We warned them about that before the game.

"It was partly down to us. We spent all week on attacking and width and we really took it for granted that they wouldn't attack; they did."

Strachan raised a few eyebrows prior to the match with his team selection with Russell Martin the only recognised centre-half in a three-man defence and the Scotland boss admitted the system hadn't worked as well as he planned.

"It got us four goals, but I was expecting that system to work a lot better than that. The goal kind of threw us a bit," the Scotland boss said.

"In any system you are hoping that your players will play to a level that you imagine, but I think in the first 10 minutes they gave away the ball eight or nine times. That's too much in international level, no matter who you are playing against."

Scotland now sit level on points with world champions Germany in Group D and are very much in contention to qualify for Euro 2016, so Strachan declared himself happy at the halfway point in the campaign.

"I have been delighted with the performances and after five games we've got 10 points. I think we're all happy with that and we can head into the second half of this group feeling quite good about ourselves," Strachan said.

"I look back at all the performances and I think the four games before this were all terrific. This wasn't one of our best, but we got through it and scored six goals."

Scotland next face a crunch match away to the Republic of Ireland in Dublin on June 13.