Nadal, 36, admitted playing through pain in his foot en route to a record-extending 14th Roland Garros title three weeks ago. He won one of his two exhibition matches on grass last week at the Giorgio Armani Classic in Hurlingham.
The Spaniard, who hasn't played competitively on grass in three years, is seeded second at Wimbledon this year, behind top seed and three-time defending champion Novak Djokovic.
On the eve of Nadal's first Wimbledon campaign in three years, Lopez said that 'everything is positive' about his ward. However, the former doubles player noted that grass can be an unforgiving surface, but Nadal's foot hasn't been a worry in training.
"There are better days and worse days," Lopez told Efe (via Mundo Deportivo). "This surface does not forgive you anything, everything happens very quickly. We are training with people who serve very well. At the moment, everything is positive. The issue of the foot, which was what always worried me the most, is going well."
"We haven't analysed the draw yet, but all rivals on grass are difficult" - Marc Lopez on Rafael Nadal's Wimbledon 2022 draw
Rafael Nadal is the top seed in the bottom half of the draw at Wimbledon 2022, which starts on Monday, June 27.
The two-time champion opens his campaign for a third title at SW19 on Tuesday against Francisco Cerundolo. If he crosses that hurdle, 2017 semifinalist Sam Querrey could lie in wait.
Marin Cilic, the 2017 finalist, is a possible opponent in the fourth round. The Croat made the semifinals at Roland Garros earlier this month. Felix Auger-Aliassime, who took Nadal to five sets at Roland Garros and beat him in the Hurlingham exhibition tournament, could lock horns with the Spaniard in the quarterfinals. The in-form Matteo Berrettini, last year's finalist, or Stefanos Tsitsipas could face Nadal in the semis.
Despite Nadal facing a tricky few matches, Lopez has said that the team hasn't analysed the Spaniard's draw yet and stated that any player can be difficult on grass.
"We haven't analysed the draw yet, but all the rivals on grass are difficult because it's a special surface, and this boy comes from winning a good game at Queen's."
Rafael Nadal has won the first two Majors of the year. He has also reached the semifinals in his last two Wimbledon appearances - losing to Djokovic in 2018 and to Federer a year later.
It remains to be seen if the Spaniard will win his first SW19 title in 12 years to go three-fourths of the way to a calendar year Grand Slam - a feat last achieved by a male player (Rod Laver) in 1969.