Following last week's shock 3-0 La Liga defeat at Sevilla, Madrid were held to a goalless draw against derby rivals Atletico on Saturday.
But as the Champions League holders prepare to continue their defence of the competition, Lopetegui insists Russian champions CSKA would be wrong to think his side are vulnerable when the two teams meet at the Luzhniki Stadium on Tuesday.
"If they're thinking that this is the best time to play us, we'll have to see about that," Lopetegui said. "The players' mindset is excellent and we're really raring to go and excited for the game to get under way.
"We face a strong side on their own patch and there's no bigger motivation than that. When the Champions League hymn sounds, there's no better motivator."
Madrid, behind La Liga leaders Barcelona on goal difference, cruised to a 3-0 victory over Roma in their opening Group G game at Santiago Bernabeu last month.
CSKA came back from two goals down to draw 2-2 in their opening match in the Czech Republic against Viktoria Plzen thanks to Nikola Vlasic's last-minute penalty, and Lopetegui is expecting a stern test.
"We're up against some fine players and it'll be an extremely challenging game because this is the Champions League," he added. "It'll be a really tough game against a side of real pedigree. They've got some top players, the likes of [Alan] Dzagoev, and they're sure to put in a big performance."
But the former Spain coach would not be drawn on whether summer signings Alvaro Odriozola and Vinicius Junior, who made his debut as a late substitute at the weekend, will feature.
CSKA midfielder Dzagoev does not think Real will be any weaker without their injured stars.
"Madrid are a great club and they have enough players for two squads," he said. "They have players capable of replacing those who stayed in Madrid. I don't think that'll make it any easier for CSKA."
CSKA manager Viktor Goncharenko paid tribute to goalkeeper Igor Akinfeev, 32, who announced his retirement from international football on Monday after making 114 appearances for Russia.
"Speaking as a fan it's a shame, but speaking as a coach he'll be able to focus 100 per cent on CSKA," Goncharenko told a press conference.
"I hope we can give him some more easy games. He's in good shape and is at the right age to continue playing at the top."
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