MOSCOW, June 20 (Xinhua) -- Portugal coach Fernando Santos admitted his side might need tactical changes after grinding out a 1-0 victory over Morocco in their World Cup Group B fixture here on Wednesday.

The European champions went ahead through an early Cristiano Ronaldo header but the team struggled to create chances thereafter as Morocco dominated possession and had six more shots on goal.

"We started well and we put the pressure on them," Santos told a news conference after the match. "We had some of the ball but it was a difficult game. Just like against Spain, we weren't able to hold on to the ball, but we have to deal with that. We ran out of lungs. We might have to make some tweaks in the strategy.

"I think Portugal played a great game. Morocco also put in a good performance. They challenged us. For Morocco it's maybe an unfair result. But that's football. If you score more you win."

Portugal started in a 4-4-2 formation, with Goncalo Guedes alongside Ronaldo in attack. But Santos was forced to switch to 4-5-1 in the second half in a bid to quell Morocco's midfielder dominance.

The move had little impact and left Ronaldo isolated in the final third.

"We needed to move players into the middle of the pitch to win back possession," Santos said. "Ronaldo was playing in a position that is not best for him. In some aspects this was similar to the Spain match. We started to push higher after 15 minutes. The dynamics were slow. We have to improve in that area. We were good defensively, but we need to do better. We know that we have to change and get more possession of the ball."

The result leaves Portugal with four points from two matches, following their 3-3 draw with Spain on Friday. The Iberians might already have done enough to advance to the knockout stage and can finish top of their group with a convincing victory over Iran on Monday.

"We have four points which is good," Santos said. "But nothing is decided yet. Morocco probably has few chances [of progressing]. But the other teams have possibilities. We really have to play well against Iran and then we'll see what happens."

Santos rejected suggestions that Pepe committed a foul moments before Ronaldo's goal and said the center-back was himself infringed upon.

"The [Morocco] player pushed Pepe and all he did was defend himself against that," Santos said. "The first foul was by the Moroccan player. There was no refereeing mistake. If anything there should have been a penalty."