The United States extended their lead to 10½ to 5½ and need just 3½ points from Sunday’s singles matches to retain the Solheim Cup after day two in Iowa.
European pair Jodi Ewart Shadoff and Anna Nordqvist won their fourball 4&2, but the US took the remaining three rubbers on Saturday afternoon.
Earlier the teams shared the morning foursomes, with two points each.
The contest concludes with Sunday’s 12 singles matches and Charley Hull is expected to return for Europe.
England’s Hull sat out the whole of Saturday’s play with a wrist injury.
The tee times for Sunday have been moved forward to 3.31pm BST, due to the threat of bad weather.
The US need 14 points to retain the trophy, while Europe need 14½ points.
With the US leading 7½ to 4½ after the morning session, Europe desperately needed points on the board.
Nordqvist and Ewart Shadoff were first in the club house after the fourballs, with a comprehensive win over Angel Win and Lizette Salas.
Sweden’s Nordqvist, who is recovering from a bout of glandular fever, has won all three of her matches this week.
Brittany Lang and Brittany Lincicome soon restored the Americans’ advantage as they narrowly beat Mel Reid and Carlota Ciganda.
Lang’s birdie on the 18th ended the European pair’s stubborn resistance, having fought back from being three holes down through seven.
Cristie Kerr, who became the US’ record points scorer earlier in the day, chipped in for an eagle on the 15th to put her and Lexi Thompson three up against Catriona Matthew and Georgia Hall.
Matthew was just short on a long birdie attempt on the 16th as Kerr and Thompson took the tie 4&2.
Paula Creamer and Austin Ernst then completed their win, beating Karine Icher and Madelene Sagstrom 2&1, to stretch the US advantage to five points.
It is the first time since 1998, that the US has led going into the singles matches.
|Saturday’s fourball results|
|Reid/Cigana (Eur) v Lang/ Lincicome (US) US won 2 up||Icher/Sagstrom (Eur) v Creamer/Ernst (US) US won 2&1|
|Nordqvist/Ewart Shadoff (Eur) v Salas/Yin (US) Europe won 4&2||Matthew/Hall (Eur) v Kerr/Thompson (US) US won 4&2|
Kerr sets US points record
Kerr and Thompson got the US off to a winning start on Saturday, winning their rubber 5&3 as the European pairing of Shadoff and Carolina Masson won just one hole.
Kerr’s victory saw her become the all-time highest US points scorer in the Solheim Cup on 19, surpassing team captain Juli Inkster.
Creamer and Ernst won their match by the same margin as they outplayed Mel Reid and Emily Pedersen, as Creamer, playing in her seventh Solheim Cup, also reached a milestone, passing Inkster as the all-time American points winner in foursomes matches with 8.5 points.
Nordqvist and Georgia Hall got Europe on the board, winning 3&1 against Stacy Lewis and Gerina Piller, before Icher and Matthew edged their rubber 2&1 against Michelle Wie and Danielle Kang.