Portugal's first division will use video replay for all league matches beginning with the 2017-18 season, the Portugal FA said in a statement on Thursday.
Its implementation will cost €1 million, according to Portugal newspaper A Bola. Federation president Fernando Gomes admitted that he expected next season to be one of trial and error with the goal of full implementation for the 2018-19 season.
"We have always wanted to give the referees the best possible condition to carry out their duties, which have never been easy," federation president Fernando Gomes said. "The goal of the federation has always been to give our referees the best possible preparation and training and to make available for them the best tools so that they can exercise their function. Our goal is that the officials make fewer mistakes with this tool and we are convinced that it [video assistant referees] will be very important in minimising the margin of error."
Gomes added that the federation has already run nine tests offline but plans to go live for the Portuguese Cup final on May 28.
VARs can be used to review major decisions, including goals, penalty incidents, red cards and cases of mistaken identity. The VAR can either notify the referee, or the referee can ask the VAR for help. The final decision, as ever, rests with the referee.
Gomes said that the International Football Association Board (IFAB) has already cleared the way for the move.
"We know that the 2017-18 season will be one of testing and the VAR will be definitive for the 2018-19 season," he said. "IFAB, depending upon how capable they judge each federation to be, can authorise the official use [of VAR]. And we have already received an indication that this can be possible in our case."
FIFA is testing VARs ahead of their possible use at the World Cup, and the system ruled out a goal that had been given for France, and later overruled a linesman to grant Spain a goal during a friendly in March that saw Spain win, 2-0.
The IFAB approved experiments with VARs last year. UEFA research showed that in the last few seasons of Champions League football, linesmen got around 95 percent of offside calls correct.