Alina Kovaleva of the Russian Curling Federation (RCF) skipped her team to two more wins on day two, including a victory over Canada, to take the outright lead at the World Women's Curling Championship in Calgary.
The RCF started their day with a 8-5 victory over Stefania Constantini's Italy, before showing they are serious contenders for a medal by mounting a comeback to defeat Kerri Einarson's Canada 8-7 at the WinSport Arena.
Kovaleva's rink hit Canada for three in the eighth and finished off the job in the final end with a single point with the hammer.
They now possess a record of four wins from four matches.
Anna Hasselborg's Sweden also remained undefeated, winning 7-4 against Marie Turmann's underdog Estonia side before hitting Madeleine Dupont's Denmark for four in the ninth end of their match, ending it 9-3 ahead.
Only playing one match each on day two, Silvana Tirinzoni's Switzerland and Eve Muirhead's Scotland remained undefeated too, with 3-0 records.
Switzerland crucially defeated Canada 8-5, overturning a two-point deficit by scoring three with the hammer in the eighth end and stealing for another two in the ninth.
Scotland won 7-6 against Daniela Jentsch's Germany, who are playing the tournament with only three players due to a COVID-19 outbreak.
Despite the smaller team, Germany recorded their second win of the tournament with a 10-9 win over Kim Eun-jung's South Korea in the late draw.
Tabitha Peterson of the United States recovered from a winless day one to pick up two victories on day two.
The US emphatically thumped South Korea 11-5, before defeating Italy 7-5, partly due to scoring four against the Italians in the fourth end.
Han Yu's China had a mixed day, starting it off by being demolished by Denmark 14-5.
Despite hitting the Danes for four, Denmark replied right back with four of their own followed by a steal for three.
Dupont's Danish side then hit China for five in the seventh end to record a high-scoring win.
Later, China defeated Sayaka Yoshimura's Japan 5-2 in a must-win match between two playoff contenders.
Anna Kubešková's Czech Republic join Han's rink on a 2-1 record, following an 8-7 win over Estonia.
The World Women's Curling Championship continues tomorrow.