Rob Page says Wales' versatility was key to their 1-0 win over Republic of Ireland.
The Red Dragons struggled to break down a stubborn Irish side and reverted to a back four in the second half of the Nations League contest at Cardiff City Stadium after initially being in a 3-4-3 system.
It was a tactical tweak that reaped huge rewards as David Brooks notched his second international goal to earn Wales all three points in the capital.
And Page admits he had to have some stern words with his players at half time after a fairly lacklustre opening 45 minutes from his troops.
"I think we gave the ball away cheaply in the first half. It was very frustrating and I said that to the players at half time," said Page.
"We caused ourselves more problems than Ireland if I'm being honest.
"We invited pressure into our box and we gave cheap free-kicks away. That disappointed us a little bit.
"We decided to change the shape late on, and it worked for us. We'll take the clean sheet, the three points and look forward to a big game on Wednesday.
"We've always had a plan B for if things aren't quite going your way, and that was it again today."
Brooks has been unable to have a major impact on the international stage due to ankle injuries.
However, he showed signs of returning to his former self against Stephen Kenny's men.
And Page admits the Bournemouth star can be a huge asset for Wales when fully fit.
"He scored two for his club last week and he's come in and scored a really big important goal for us," added Page.
"I was with him in Ireland when he went over on his ankle and saw how low he was after that, which was frustrating for him and horrible for us to see.
"He had a little setback, but thankfully, he's come back and growing stronger as the weeks go on.
"To have a fully fit David Brooks is absolutely brilliant. He showed glimpses of his quality again tonight.
"He can mix it up, and he can score headed goals in the six-yard box as well!"
Jonny Williams was not included in the squad to face the Irish due to a slight hamstring issue.
But Page has revealed the Charlton Athletic man is expected to be available for Wednesday night's clash with Finland.
"Jonny will be assessed again tomorrow," added Page.
"He tweaked his hamstring in training, so as a precaution we pulled him out.
"We'll assess him and we'll know if he's got a chance of playing on Wednesday.
"The likelihood is that he'll be OK, so that's a positive."
Wales will finish at the summit of their group if they avoid defeat Finland.
Kick-off against the Finns is at 7:45pm on Wednesday night.
