Ivo Karlovic and Radek Stepanek have both withdrawn from Wimbledon starting on Monday because of injury.
Stepanek was seeded 22 but is out with knee trouble, which will also sideline him for the Czech Republic’s Davis Cup quarter-final with Chile next month.
The big-serving Croatian Karlovic was due to have been seeded 25th, but has been troubled by a foot injury.
Victor Hanescu of Romania has been elevated to number 31 seed with the remaining seed still to be announced.
At 6ft 10, Karlovic is the tallest player on the tour and at last year’s Championships reached his first Grand Slam quarter-final, losing to Roger Federer.
Karlovic was also thought a formidable opponent on grass because of his unique serve, which produced a remarkable 158 aces on his run to the last eight at SW19.
The 31-year-old reached round four of the Australian Open this year, before he was beaten by Rafael Nadal.
Stepanek, also 31, reached the final of the Brisbane International in January but has failed to survive beyond the second round of any other tournament this year, losing in the first round of the Australian Open to Karlovic.
He announced in March that he was suffering from fatigue syndrome and withdrew from last week’s grass-court tournament in Halle, Germany, because of throat inflammation.
His best finish at Wimbledon is also the quarter-finals, which was in 2006.