Lufthansa lost an appeal to a Frankfurt labour court, but is making a further legal challenge that could go late into Tuesday evening.
The pilots' strike, called over a pay dispute, will affect around 100,000 passengers, Lufthansa said.
The industrial action is part of a long-running pay dispute at Lufthansa.
The pilots' union Vereinigung Cockpit (VC) has organised 14 strikes since April 2014.
Short and medium-haul flights from Germany will be affected from 00:01 to 23:59 local time (23:01-22:59 GMT).
Flights by Lufthansa's other airlines including Eurowings, Swiss, Austrian Airlines, Air Dolomiti and Brussels Airlines are not affected by the strike, the airline said.
Pay talks between the Vereinigung union and the German airline broke down earlier this month, and Lufthansa said the union had "consistently rejected the offer" of mediation.
The union is calling for a 3.7% pay rise for 5,400 pilots dating back to 2012.
Lufthansa, which is facing increasing competition from budget rivals, offered a 2.5% increase over the six years until 2019.
Meanwhile, a separate dispute with cabin crew at Lufthansa's low-cost subsidiary, Eurowings, led it to cancel more than 60 flights on Tuesday.
German airline Lufthansa is making an eleventh-hour court appeal to halt a planned pilots' strike that will cancel 900 flights on Wednesday.