Both squads need a victory to stay in the tournament, and Qatar will "fight tooth and nail" on the pitch in Seattle, Lopetegui said.
Qatar are coming off a 6-0 loss to Canada. Defender Homam Ahmed and midfielder Assim Madibo both received red cards in the match.
The latter was sent off after tackling Ismael Kone and breaking the Canada midfielder's leg, and Lopetegui said Madibo had visited Kone in Vancouver.
"He (Madibo) was very, very affected by this injury," the coach said. "Never was it his intention."
The Maroons' drubbing by Canada is now in the past for them.
"Now, we are focusing on the challenge tomorrow that we have," Lopetegui said.
Qatar and Bosnia both have one point in the group standings.
"Pressure? Nothing," the coach said. "We have ambition and excitement."
This is the first time Qatar have qualified for the World Cup. The country hosted the 2022 edition, which earned the team an automatic slot in the tournament.
Lopetegui described Bosnia as strong "physically and technically", with several dangerous forwards and wingers, and noted that they had eliminated Wales and Italy to get to the World Cup.
"They have a lot of solutions," he said. "We have to use our strengths and be the best team possible."
Forward Ahmed Al-Eddin said the Qatar squad had stuck together after the Canada mauling.
Seeing supporters wearing traditional Qatari clothing in the stands at the Canada match and the 1-1 draw with Switzerland had been inspiring.
"It made us actually feel hope, as if we were playing in Qatar, not in the US," Al-Eddin said. "And God willing, we will try to give back at least one small part, one very modest part of what they have been giving to us along the way."