Interwetten Honda will start its second MotoGP race weekend without Hiroshi Aoyama at Catalunya, which should also be the last for Kousuke Akiyoshi as a stand in.
Aoyama is likely to be sidelined for at least two months after fracturing a vertebra at Silverstone.
HRC test rider Akiyoshi was called-up at the last minute for Assen and Catalunya, but a more competitive replacement is being sought from the German Grand Prix at Sachsenring.
Interwetten are believed to be talking with three different riders and the number one criteria is MotoGP experience, which at least two of the unnamed riders are said to have.
2009 MotoGP podium finisher Alex de Angelis, now in Moto2, is the hottest rumour for the seat, but team manager Daniel Epp insists no decision has been taken.
"Kousuke will, as he already did in Assen, ride Hiro's bike for us in Barcelona again,” said Epp. “Also the Yamaha Test rider [Yoshikawa] will be present there to substitute for the injured Rossi and I am looking forward to the battle between the two test riders. Of course I hope Honda will win.
“For the races from the Sachsenring we are still looking for a replacement. We have a few options, but we are not decided yet. Until Hiro is back with us we need a stable solution,” Epp added.
Akiyoshi finished 15th and last - and one lap down - on his MotoGP race return at Assen. The 35-year-old knows his only realistic goal is to beat 41-year-old Yoshikawa this weekend.
"Assen was a completely new track for me, but I liked it,” he said. “Barcelona I know, I have been there before, but that was quite a while ago. I heard that also the test rider of Yamaha will take part in the race and I look forward to the battle with him. I hope I will win it."