Lopetegui keeping Spain door open for Costa
The striker has not played for Chelsea since last season and cannot appear for new club Atletico Madrid until their registration ban is lifted at the beginning of next year.
Costa was unsurprisingly omitted from the Spain squad for this month's friendly matches with Costa Rica and Russia but Lopetegui insists he has not discounted him from his thinking.
Asked about the 29-year-old, the coach told a news conference: "We'll see from January, but he's in our plans."
Lopetegui also stressed that David Villa and Dani Parejo could earn a place in the squad in future.
Villa, 35, was recalled for the World Cup qualifiers in September but has been left out of the latest group, as has Valencia captain Parejo, who had been tipped for a place following his side's strong start to the season.
"He's playing excellently and he could be called up at any time," Lopetegui said of the 28-year-old, before adding of Villa: "He isn't in today, but he could be in the future."
For the time being, Lopetegui hopes to get a better look at Liverpool full-back Alberto Moreno and Lazio's Luis Alberto, both of whom were surprise inclusions.
Moreno last played for his country in 2014, while Luis Alberto is uncapped at senior level.
"He's been playing at a very high level for Lazio for some time," Lopetegui said. "He was on the point of being called up a few times and now we want to see him up close, because he understands football in the way we like.
"[Moreno] is proper first-choice at Liverpool, he's playing all the time and I know him very well from the youth teams. Now I want to see him up close."
OFICIAL | Lista de la @SeFutbol para los amistosos ante Costa Rica y Rusia / Spain's call up #SEFlive pic.twitter.com/ENlk6JJ2mv
— Selección Española (@SeFutbol) November 3, 2017