Rafael Nadal and Feliciano Lopez
Rafael Nadal lost the last two meetings against Feliciano Lopez. Pictured: Rafael Nadal of Spain congratulates Feliciano Lopez of Spain following their match on Day 6 of the Western and Southern Open at the Lindner Family Tennis Center on Aug. 20, 2015, in Cincinnati, Ohio. Maddie Meyer/Getty Images

Roger Federer is a tougher opponent on the court than Rafael Nadal, according to Feliciano Lopez.

Federer and Nadal share one of the biggest rivalries in sports, but the story of last year was their career resurgences. The duo returned from long injury layoffs to win a combined 13 titles as they shared the four Grand Slams between them and ended the year in the top two places of the rankings.

However, while Nadal boasts a superior head-to-head record over Federer throughout the years and finished 2017 as world No. 1, a key theme particularly since the beginning of last year was the Swiss legend's recent dominance in their battles.

Federer has won the last five meetings between the pair, including four last year, as the tables seem to have turned with the record now standing at 23-15 in Nadal's favor.

Lopez has played against them numerous times and while he considers both "extremely complicated" to play against, he believes Federer is the tougher opponent over his Spanish compatriot, notably having zero wins in 13 matches against the former while he boasts four wins in 13 matches against Nadal.

"Rafa has some qualities and Roger has others, but playing against them is extremely complicated," Lopez told Spanish publication Marca, as per the Express. "I was lucky to play more against Federer because we have faced each other since childhood. I always say that the toughest rival I faced on-court is Federer, followed by Rafa."

Federer continued his resurgence in 2018 as he went on to win the Australian Open for the second year running before becoming the oldest world No. 1 in tennis history during his win at the Rotterdam Open in February.

Nadal meanwhile, has not featured competitively since the Australian Open, as he pulled out of his quarterfinal clash with Marin Cilic in the fifth set due to a hip injury.

The 16-time Grand Slam winner was expected back sooner, but eventually pulled out of the Mexican Open, BNP Paribas Open and Miami Open, though he became world No. 1 again due to Federer's results in the latter two events.

Nadal did recently return for Davis Cup action however, as he represented Spain last week and won both his singles matches, including a straight-set win over Alexander Zverev. The manner of the win particularly impressed Lopez, especially given his fellow Spaniard's injury problems and time away from the sport.

“He [Nadal] surprised me in Valencia, after a lot of time without competing, the confidence he had when playing," Lopez, who was also a part of Spain's Davis Cup squad, said. "It's not really normal."

Nadal's performances are a good sign especially with the clay-court season approaching. He is expected to feature in the Monte Carlo Masters which commence on April 14 as he looks to emulate last season where he won every clay event he took part in other than the Rome Open.