Portugal boss Roberto Martinez sees Cristiano Ronaldo's "incredible" achievement of 900 career goals as an "inspiration for football".

Ronaldo netted his landmark goal on Thursday, scoring Portugal's winner in a 2-1 Nations League victory over Croatia.

The 39-year-old was already the leading goalscorer in the history of the game.

And Martinez feels nobody can put a limit on what Ronaldo is still able to achieve.

"I don't think scoring 900 goals is easy. It's a historic achievement, incredible, an inspiration for football," Martinez said ahead of Portugal's clash with Scotland.

"I don't think anyone can say that Cristiano can't do something. It's incredible what he's achieving, what he's doing in football.

"For us, the goal is collective. That he helps the national team."

Scotland lost 3-2 at home to Poland in their Nations League opener, but Martinez is expecting a fierce test on Sunday.

"Our players know the intensity of British football. Scotland have that. A lot of intensity, fast attacks, experience. We know the difference, but Scotland are objective, vertical, but have the quality to keep the ball," Martinez said.

"The last two games have shown that they want to win. They've lost their last few games after the 90th minute, they're objective, they've got top-class players. They're experienced and talented.

"It's not just a British team, a physical team, but a team with lots of skills and the game will be very competitive. We've prepared for that."