Gary Caldwell insists the Celtic players need to learn to be more clever in Europe after a contentious free-kick led to their Champions League defeat by Villarreal in El Madrigal.
When Yellow Submarine striker Joseba Llorente went to ground after Paul Hartley's challenge, referee Viktor Kassai awarded a free-kick which Marcos Senna curled past Artur Boruc for the 67th-minute winner which leaves Gordon Strachan's side bottom of Group E with one points from two games.
Caldwell, like most of the Celtic camp, was fuming at the free-kick award.
The Scotland defender said: "The free-kick was soft and I thought they got a lot of soft free-kicks in the second half around our box.
"They are very clever, they go down very easily at times and it's something that we have to learn.
"We have to do it in their half, to get those free-kicks to give us breathing space."
Strachan employed a 4-5-1 formation with Georgios Samaras leading the line and although the Greece international missed a great chance before the interval, Caldwell believes the Scottish champions can be pleased with their overall performance.
He said: "Everyone can see it worked very well. I thought we were the better team in the first half. "We played very well and defended well.
"We also posed a threat going forward and had the better chances.
"Georgios played well in the first half and the goalie made a good save so there was not much more he could do.
"But 10 minutes into the second half they got their foot on the ball and started to play and we struggled to get out.
"We just couldn't hold on and the goal, a soft free-kick, was disappointing."
Celtic travel to Old Trafford for their next game needing a win if they are to have any realistic chance of qualifying for the last-16 for the third season in succession.
Scotland international Caldwell remains defiant despite the Hoops now having just one point away from a possible 48 home at this stage of the competition.
He said: "There is still a long way to go. We have two home games and we play Aalborg away which is winnable.
"I think we would play a similar style at Old Trafford and see what we can get.
"If we play like that we did last night, we will be good enough to get through."