Gemma Davison marked her Women's Super League debut for Chelsea with both goals in their win at Notts County.
Davison tested Lady Magpies keeper Carly Telford with a fierce angled shot before coolly slotting the visitors ahead on 23 minutes.
Ex-Chelsea forward Rachel Williams then met an Alex Greenwood corner to head home the leveller soon after.
Ji So-Yun hit the post for Chelsea before Davison secured the win from the penalty spot after Amy Turner's foul.
With both side easing through the fifth round of the FA Women's Cup with convincing wins over lower league opposition last week, their WSL 1 season opener looked to be a truer test of two of the title favourites' credentials.
Chelsea started brightest, with Eniola Aluko's pace putting Rick Passmoor's side under plenty of pressure.
Winger Davison, who helped Liverpool win last season's WSL 1 title ahead of Chelsea on goal difference, called Telford into action for the first time at her near post, with the keeper tipping the well-struck shot over the bar.
From the resulting corner Drew Spence flicked an effort just wide, while at the other end Ellen White had a good close-range chance deflected over the bar by Katie Chapman.
Davison then met a Spence pass to put Chelsea ahead with a neat low finish past Telford, but the lead was short lived as Williams made it 1-1 two minutes later.
Williams' goal came less than three months after the 2011 WSL top goalscorer and England international moved to Meadow Lane from Chelsea.
As heavy rain lashed down after the break both sides struggled to push forward with any meaningful intent for long periods.
However, after conditions cleared So-Yun got on the end of a fine Aluko cross to brush the post with a header before Davison picked herself up to net her second from the spot.
Notts County: Telford, Greenwood, Buet, Bassett, Turner, Whelan F, Walton, Crichton, Clarke (Whelan A 88), Williams (O'Sullivan 73), White
Substitutes not used: Draycott, Susi, Sigsworth, O'Neill
Chelsea: Lindahl, Blundell, Bright, Fahey, Rafferty, Coombs, Davison (Groenen 90), Chapman, So-Yun (Borges 76), Aluko (Banusic 87), Spence
Substitutes not used: Hourihan, Flaherty, Brett, Meiwald
Referee: Ian Dudley