Cristiano Ronaldo believes Real Madrid are capable of becoming the first team to successfully defend the Champions League.

No club has retained the European Cup since the revamped format was introduced by UEFA for the 1992-93 season, AC Milan in 1990 being the last side to win the famous trophy back to back.

Madrid are the most successful team in the competition's history, winning two of the last three tournaments to secure their 10th and 11th continental titles.

They begin their latest campaign at home to Ronaldo's former club Sporting CP on Wednesday.

And the star forward feels the team, coached by Zinedine Zidane, can progress to the latter stages yet again. 

"It's a challenge, it's a great challenge, and I think at Real Madrid we have a chance to win it again," he told the UEFA website.

"We know it's a very difficult competition, but nothing is easy so we'll try. 

"We'll take it match by match, and first think about the group stage, as in my opinion it's a strong group," he added, with Madrid, in addition to Sporting, drawn against Borussia Dortmund and Legia Warsaw in Group F.

"We'll see how the competition unfolds. But think positive - that it's possible to win it again."

Adding Euro 2016 glory with Portugal to a third Champions League success has left Ronaldo acclaiming the previous season as a personal high point.

"In terms of trophies it was possibly the best year of my career," he said.

"After winning the Champions League, winning the European Championship with my country capped an extraordinary year for me.

"Trophy-wise it was the best, I've never had a better year. The same goes both collectively and individually, because I was top scorer in the Champions League and had a good European Championship, and we were able to win the two biggest trophies. 

"So it really was a top drawer, excellent season for me."

Having suffered a knee injury in the final of the European Championship, Ronaldo made a scoring return to competitive action in Madrid's 5-2 LaLiga win at home to Osasuna on Saturday.