World number two Rafael Nadal says "it doesn't seem right" that he could be seeded behind world number three Roger Federer at Wimbledon.

Wimbledon seeding is different from the other Grand Slams in that it does not always follow world rankings and is affected by grass-court performances.

It means Federer may be seeded ahead of Nadal, who could be in the same half of the draw as Novak Djokovic.

"It's just Wimbledon that does it," said 12-time French Open winner Nadal.

Speaking to Spanish TV station #Vamos, Nadal added: "If everyone did it, I think it would be appropriate or correct. Either way, being second or third seed, I have to play at the best level to aspire to the things I aspire to.

"It is better to be second than third, but if they consider that I have to be third, I will accept."

Wimbledon seedings will be announced on Wednesday and Nadal, 33, is likely to be behind defending champion Djokovic and eight-time winner Federer, who won his 10th title at the grass-court tournament in Halle last week.

The Spaniard lost in the Wimbledon semi-finals to world number one Djokovic last year but had not made it past the fourth round in his five previous appearances.

Nadal's viewpoint was supported by Djokovic, who played at the Boodles exhibition event at Stoke Park in Buckinghamshire on Tuesday.

"It's their rules and you have to respect it, although it's a little bit surprising to be honest," said Djokovic.

"Roger is the greatest of all time and has won the most Wimbledon titles of any player in history and if any player deserves it it's him, but at the same time it's Nadal that he is taking over (from as) the second seed."

If he is seeded third, Nadal might have to beat Djokovic to reach the final.

The world's top 32 players will be seeded, but the order may not follow that of the world rankings.

Wimbledon's system favours grass-court specialists - taking a player's ATP ranking points, doubling the points earned at grass-court tournaments in the past year and adding on 75% of the points earned on grass the previous year.

The women's seedings follow the WTA ranking list but changes can be made for a "balanced draw", which is why Serena Williams, ranked 183rd before last year's tournament, was 25th seed in 2018.

The 2019 tournament begins on Monday.