Josh Coburn netted a double as Millwall kicked off their Championship campaign with a comfortable 2-0 win over 10-man Bristol City at Ashton Gate.
The home side went a man down after 36 minutes when midfielder Adam Randell was shown a second yellow card for a foul to prevent a counter-attack.
Five minutes later Coburn converted a low Ryan Leonard cross from the right with a near post volley.
Coburn then doubled the advantage after 50 minutes, taking advantage of wretched defending to net unchallenged with a downward header from 10 yards.
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The result meant that Michael Skubala's reign as City boss has begun with two home defeats, following the shock Carabao Cup exit at the hands of League Two Walsall, and without his side scoring a goal.
Skubala brought in Rob Atkinson at the back in place of the injured Cam Pring, along with attackers Dom Ballard and Yu Hirakawa, while Alex Neil gave Millwall league debuts to Tairyk Arconte and Jenson Metcalfe.
The visitors were the better side before Randell's dismissal. Camiel Neghli shot narrowly wide and Casper De Norre headed over inside the first six minutes.
Ballard sent a shot flashing wide for City from Lorent Tolaj's 12th-minute knock down, but it was a rare moment of anxiety for Millwall goalkeeper Lukas Jensen.
Coburn claimed a penalty when going down as he rounded City goalkeeper Sam Tickle, but referee Lewis Smith saw no contact and booked the striker for simulation.
Randell's departure, having been cautioned for a foul 13 minutes earlier, saw Millwall crank up the pressure and Coburn's goal came as no surprise as the visitors went in front.
The Lions began the second half like the first and Metcalfe had a shot blocked in a crowded box before Coburn's close-range effort was saved by Tickle.
City had introduced midfielder Joe Williams for Hirakawa in an effort to tighten up, but looked wide open at the back as Coburn grabbed his second.
Moments later it should have been 3-0 as Arconte contrived to hit a post when unmarked following a cross from the right.
Tolaj shot over in a rare City raid, but their defence looked all over the place as Metcalfe headed over.
Skubala responded with a triple substitution, sending on Sam Bell, Emil Riis and Jed Wallace for Tolaj, Ballard and Sam Greenwood.
Wallace was soon in the action, firing inches over from a free-kick, but the damage had already been done and Millwall could have added a third but substitute Mark Syles sent an effort wide from 25 yards.
The managers
Bristol City's Michael Skubala:
"The sending-off changed the game. After an edgy start, we were just starting to get into the match and put together some threatening moves.
"I haven't seen the incident back, but the referee told me Adam pulled a shirt and if that was the case after already being booked, it was not a great thing to do because then it became a very difficult afternoon for us.
"We had started to get further up the pitch and the game was settling into the close contest we expected. We were getting into some of the spaces where we planned to hurt their back-line.
"The sending-off was not an excuse for the two goals we conceded, which came from moments we need to do better in. If we had managed to keep it at 1-0 for longer, I'm sure we could have created a situation to equalise.
"When you sign so many new players they have to link and achieve some cohesion, which takes time. I thought we were seeing signs of it when the sending-off happened.
"That's the frustration. The supporters were fantastic and I'm disappointed we were not able to give them more to cheer."
Millwall's Alex Neil:
"We started really well until some silly refereeing decisions to overturn throw-ins and turn a goal kick into a corner disrupted things.
"I think there will be a lot of frustration over such decisions in Championship games this season. The referee actually had a good game, but the new rules are there to prevent teams slowing play down and killing games in the closing stages. Neither ourselves nor Bristol were trying to do that.
"We were told common sense would be applied and I didn't think it was so early in the match.
"The sending-off was another talking point. The second booking for their player was right because the foul prevented us launching a counter-attack.
"I can't remember the first one if I'm honest, but what I can say is that we turned in a really strong team performance, moving the ball well and showing an abundance of quality.
"We hit a post and had a goal disallowed. It was an excellent display and we thoroughly deserved to win.
"Josh Coburn was one of the reasons we finished last season strongly. I didn't think he showed that form in pre-season and we talked about it, but today he scored two goals and showed he can be one of the best strikers in the Championship."
What the result means and next fixtures...
- Championship fixtures