Yamaha rider Lorenzo and Repsol Honda counterpart Pedrosa both sat out last weekend's race in Germany due to collarbone injuries.
Pedrosa's team-mate Marquez took full advantage by claiming the race win and moving to the top of the standings in time for his first visit to Laguna.
While Marquez will cross the Atlantic in high spirits, reigning world champion Lorenzo is badly beaten up.
The Spaniard was already nursing the broken left collarbone he suffered at Assen when he fell in practice at the Sachsenring, landing on the same area and bending the titanium plate put in place to help stabilise the injury.
Pedrosa then crashed on Saturday morning in Germany, suffering a fracture to his left collarbone.
Lorenzo, who trails Marquez by 11 points in third place, had initially indicated he would miss Laguna after undergoing surgery in Barcelona, but has instead decided to give it a go at a track where the riders get little respite.
"Finally we have decided to go to Laguna Seca," he said. "Following the final medical check and after speaking with Dr Rodriguez we are going to try.
"At the beginning I seriously thought that it might have been convenient to take the necessary time to recover and be back at Indy but in the last two days I have felt much better so now I want to be there, although I will try to not take too many risks.
"I want to be there also for the fans, for the championship but especially for my team, who are waiting for me.
"I want to thank everybody for all the support I have received so far and I want to say thank you to the doctors who took care of me after the crash at Sachsenring, both at the Clinica Mobile and at the Hospital General de Catalunya, especially Drs Rodriguez and Cots."
Pedrosa, who is two points adrift of Marquez, said: "After a disappointing weekend in Germany, I'm happy to be feeling better again and thankful that my shoulder wasn't completely broken, even if a fracture is still not the best thing to happen.
"Now I need to get back on track to see what condition I'm in and hope we can have a good weekend."