The 2020 Tirreno Adriatico is available LIVE and on demand on FloBikes for viewers in the U.S. and Canada.
The Bora-Hansgrohe rider cemented his position at the top of the overall standings by making it two from two at the end of the 201 kilometer ride set up for sprinters between Camaiore and Follonica.
Taking third was Ackermann's compatriot Rick Zabel riding for Israel Start-Up Nation, the team Chris Froome joins from Ineos next season.
The four-time Tour de France champion is in the Tirreno peloton, using the eight-stage race to tune-up for the Vuelta a Espana.
His Ineos teammate and 2018 Tour de France winner Geraint Thomas are also in Italy ahead of his main target, the Giro d'Italia starting on October 3.
Tuesday's action was marked by a breakaway bid from Umberto Orsini (Bardani-CSF) 26km out, only to be caught by the pack with the sprinters poised to pounce.
Ackermann leads by eight seconds from Colombian Gaviria going into the longest stage of the race, Wednesday's 217km ride from Follonica to Saturnia.