Goals from Ellie Carpenter and Kadeisha Buchanan were enough to give Chelsea their second win in this season's Women's Champions League on Wednesday to join Arsenal and Lyon at the top of the table.
Bayern Munich came from two goals down to draw with Real Madrid while Servette thrashed OH Leuven 5-1.
Chelsea, who reached the final in 2020-21, opened their campaign with a win and a draw despite scoring just once in their first two games.
They looked nailed on for another win in the first half at Plough Lane as they dominated the game without getting a goal.
That changed in the 51st minute when Wieke Kaptein cut the ball back for substitute Carpenter, making her 50th Champions League appearance, who slid the ball under the goalkeeper Rachele Baldi.
Melvine Malard missed a golden chance to put the game to bed but Buchanan made it 2-0 a minute from time, heading Kaptein's cross into the Roma net.
"I'm pleased with the fact we scored really early in the second half. We could probably have killed the game a little bit earlier," said Chelsea coach Sonia Bompastor.
"In these kinds of matches, if you don't kill it off, you just leave the hope for the opponent. When that's the case, they have a lot of energy and confidence.
"It's important for us in these games to be able to be clinical and ruthless as early as possible.
"But we find different ways to impose ourselves in the game and to score goals. So it's good."
Chelsea move to seven points after matchday three, behind Lyon and Arsenal on goal difference. Champions Barcelona, who have six points after winning both of their opening games, will return to the top if they beat HB Koge in Denmark on Thursday.
Marie-Antoinette Katoto scored the first two before Vicki Becho chimed in with a hat-trick off the bench in eight-time winners Lyon's 5-0 home thrashing of Inter Milan.
Arsenal got their campaign up and running with a 3-0 win over Benfica, Alessia Russo netting a hat-trick to become the highest scoring English player in European football with 23 goals.
There was a moment's silence before kick-off at the Sportpark Unterhaching in Munich as a mark of respect after at least 68 people were killed in a train crash near Madrid earlier on Wednesday.
Real Madrid, who were all wearing black armbands, took an early lead when Athenea found the net in the seventh minute.
Former Bayern forward Lineth Beerensteyn doubled the lead 15 minutes later before her old team fought back with an Edna Imade header just after the half-hour.
Momoko Tanikawa equalised in the 52nd minute with a curling shot from the edge of the box and it finished 2-2.
Swiss side Servette dispatched Belgium's Leuven 5-1 with Paola Hernandez and Gloria Marinelli scoring two goals each.