The Scots' hopes of reaching Brazil next year are all but over after taking just two points from their first four Group A games, and a hammer blow to their chances came last October when Bale scored two late goals to seal a Welsh win in Cardiff.
After James Morrison had given the visitors the lead, Steven Fletcher thought he had doubled Scotland's advantage only for the linesman, erroneously as it turned out, to rule the ball had gone behind before the striker knocked it in.
The Scots still looked comfortable until the latter stages, when Bale won and then converted a penalty before unleashing an unstoppable left-foot drive from distance with a minute remaining to give Chris Coleman's men all three points.
After Gordon Strachan got his tenure as Scotland manager off to a winning start thanks to a Charlie Mulgrew goal against Estonia in their challenge match at Pittodrie last night, attention turned to the double-header at home to Wales and away to Serbia, with Berra pinpointing the obvious danger in the first game on March 22.
The Wolves defender, 28, said: "We definitely want to get three points against Wales.
"We should have got them away from home and would have if it wasn't for Bale sticking in a world class goal and scoring a penalty.
"At 1-0 up we were comfortable, they weren't threatening us and then they got a penalty out of nothing.
"It could still have been 1-1, they weren't putting us under severe pressure but the next thing Bale sticks the ball away from 35 yards. What can you do about it?
"This is why he is rated at £40million or so, (and why) Real Madrid supposedly wanted to sign him after that.
"We know he is a world-class player and we have to limit him to very few chances.
"I played against him at club level and sometimes, when these players are on their day, there is nothing you can do but hopefully he has an off-day.
"He is one of these players who have everything, he is an athlete and he has a great touch.
"He can do nothing in a game and the next thing he puts one in the top corner.
"Against West Brom the other day, a couple of players tried to tackle him and he wasn't happy but the ball came to him and boom, he smashed it into the net.
"Sometimes you just have to put your hands up and say 'well done'.
"But as long as we are disciplined and compact, and attack and defend as a team, then we have a chance."
The former Hearts stopper insists the transition from Craig Levein, who departed last November, to Strachan was seamless and was encouraged by a solid performance against Estonia.
"The majority of the squad is still here, apart from maybe Chris Burke who came in, so it has been business as usual," he said.
"Unless you play for clubs like Manchester United where the manager is there forever, you get used to it.
"Managers come and go like players come and go.
"It is a fresh start and it gives everyone a little more energy to go and impress.
"It was 1-0 but we could have scored a couple more. There were so many substitutes and towards the end players were getting tired, but it was good to get a victory and keep a clean sheet.
"Afterwards the manager said well done and that over the piece we did quite well but that there were a few points that we could work on.
"We are not Barcelona and there are always areas that we could improve on.
"But it is always good to get a win and it gives us confidence ahead of those next two games."