Lorenzo crashed at high speed in second practice at Assen on Thursday and will miss at least this weekend's race.
"It's a great pity for Yamaha, for the team and for him as he is fighting for the championship," said Rossi.
"I hope that he comes back as soon as possible, hopefully for the next race in Sachsenring.
"I hope to do a good result because I am now the man of the team for Yamaha, for the factory team and all the guys."
Rossi has not managed a podium finish since his second place in Qatar at the start of the season, but team director Massimo Meregalli is confident that Italian can be in better shape in the Netherlands.
"Vale did two good practices, it seems the feeling he was looking for in the front is back," said Meregalli.
"Fortunately we had the opportunity to test in Barcelona and in Aragon to find it. Let's see tomorrow what we can do."
He admitted there was no point ruing Lorenzo's absence.
"This is a real pity as we were coming from two brilliant results and looking for a third," he said.
"We have to accept this, it is part of our sport.
"We wish him the best to come back as soon as possible and stronger than before."
- Sports & Recreation