First-half strikes from Felipe Santana and Mario Gotze have put Borussia Dortmund in complete control of their Champions League last-16 tie with Shakhtar Donetsk.
The Ukrainians now trail 4-2 on aggregate and need to score three unanswered goals in the second period to rescue their European campaign.
Santana added to a crucial away goal from his central defensive partner Mats Hummels in the reverse fixture with a powerful 10-yard header on the half-hour mark.
Dortmund's advantage was increased further when Gotze ghosted in-between two Shakhtar defenders and turned home Robert Lewandowski's cross.
The Polish striker had a chance to put the tie beyond doubt when he went clear before the break, but Tomas Hubschman capitalised on his hesitation to make a crucial intervention.
Brazilian Fernandinho had Shakhtar's only notable attempt of the opening 45 minutes, linking up with compatriot Taison before having a 20-yard shot blocked by Ilkay Gundogan.