PORTO, Portugal - Portugal sealed a Nations League quarter-final berth after a Cristiano Ronaldo double with a penalty and an overhead kick helped them hammer visiting Poland 5-1 in Group A1 on Friday.

Rafael Leao broke the deadlock just before the hour with a header before Ronaldo doubled the lead from the spot in the 72nd minute with a confident strike down the middle of the goal.

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The hosts then scored three goals in eight minutes through Bruno Fernandes, Pedro Neto and Ronaldo's clever strike before Dominik Marczuk got a consolation for Poland in the 88th.

"The first half was very bad for what we wanted to do, we lost focus and got frustrated. But the second half was the best I've seen," said Portugal coach Roberto Martinez.

"We've changed the mentality and increased the intensity and mutual support. We didn't let Poland play."

Unbeaten Portugal top the group with 13 points, six ahead of Croatia, who lost 1-0 away to a Scotland side who are still bottom but now level on four points with third-placed Poland.

Poland host Scotland on the final matchday on Monday when Portugal travel to Croatia.

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Portugal, who snapped Poland's two-year unbeaten home run when they won the reverse fixture in Warsaw 3-1 last month, had trouble taming the visitors in the first half.

Poland were without their all-time top scorer Robert Lewandowski, who is sidelined with a back injury, but were quick to create danger and had three attempts on target before the break compared to none by the hosts.

Bartosz Bereszynski was close to opening the scoring in the 12th minute but Portugal goalkeeper Diogo Costa was in the right spot to catch his header before he had to stretch to deny Krzysztof Zalewski's powerful shot from the edge of the box.

Both Leao and Ronaldo sent good chances above the bar just before the break before the tables turned for Portugal after the restart.

Clearly fired up, the hosts dominated possession and Leao recovered the ball inside their own box before he raced through the pitch to find Nuno Mendes on the left flank who then set the forward up with a perfect lofted pass.

Portugal were then awarded a penalty for a handball, expertly converted by Ronaldo, as they continued growing in strength and Fernandes struck from a distance to make it 3-0 when the ball bounced in off the inside of the bar.

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Neto added another one in the 83rd minute, scoring inside the near post, before Ronaldo netted his 135th goal for the national side with an acrobatic finish in the 87th.

Distraught Poland pulled a late goal back through halftime substitute Marczuk, who scored his first international goal.

The 2019 winners Portugal, who dropped their first points last time out when they were held to a goalless draw in Scotland on Oct 15, secured a fourth successive top-two finish in the competition.