Rob Edwards sent a timely reminder to Middlesbrough supporters and the Championship that he still has the magic touch in this league.
Boro bounced back from a shock Carabao Cup loss to Doncaster Rovers in the week to secure back-to-back league wins away at a fiery Den.
The 3-0 win in the capital means Boro won their first away game of a season since 2016 and start a new campaign with two league victories for the first time since 1994-95.
Millwall were excellent in the first half with Boro struggling to keep up. Then Edwards, at half-time, made some tweaks to his system.