Teenager Erling Braut Haaland scored twice more off the bench as Borussia Dortmund moved up to third in the Bundesliga with a 5-1 thumping of Cologne.
Having claimed a hat-trick as a replacement on his Dortmund debut last Saturday to inspire a 5-3 win away at Augsburg, Haaland, 19, again showed clinical finishing.
"For Erling, it's simply wonderful - five goals, two games, there are worse starts," said Dortmund captain Marco Reus.
"Especially here at home - that's why we signed him.
"That was a good step forward from us -- also from me personally," added Reus who was criticised for missing clear chances against Augsburg.
With his team 3-1 up, Haaland came on for his first home appearance with an hour gone and 11 minutes later was on the scoresheet, slamming home the rebound of a saved Julian Brandt shot.
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He then showed his speed to beat Cologne goalkeeper Timo Horn, tucking the ball into an empty net on 87 minutes.
Dortmund coach Lucien Favre explained why Haaland was again only a second-half replacement.
"He didn't train in December due to injury, therefore we have to be careful with him," said the Swiss.
"He's not ready to play from the start, we have a plan for him."