Krueger posted a 3 and 1 win over Maggie Leef at Holston Hills Golf Club.
Probst, the medalist during stroke play, fell 1-down to Leslie Folsom when Folsom chipped in at the ninth. Probst won the 11th and 12th to claim a 1-up lead and then put the match out of reach with a par on the 15th.
'I was talking to Matt Herron, my boyfriend and caddie, today walking down nine,' said Probst. 'And I said, 'When you're the top seed, people are trying to knock you off.''
Carol Semple Thompson, a two-time winner of this event, extended her own record by advancing to the match play portion for the 18th consecutive year at this event.
She holed out for eagle on the sixth to start a run of five straight holes won en route to a 5 and 4 win over Lee Ann Fairlie. Semple Thompson moves on to face Marilyn Hardy, a 3 and 1 winner.
'I hit it at the flagstick,' said Semple Thompson of the eagle. 'I don't see that well, but I was just hoping it would go in.'
Kathy Hartwiger, the 2002 champion, was the biggest winner of the day as she crushed Kate Grace, 9 and 7. That was the second biggest win in event history.
Hartwiger advances to play Ellen Port, who has won this event three times and owns the biggest win, a 9 and 8 defeat of Sue Churchich in 2001. Port was also an easy winner, as she beat Shelley Anderson 6 and 4.
Virginia Grimes, the 1998 winner, posted a 6 and 5 win over Akemi Khaiat. Grimes will take on Natalie McNicholas, a 1-up winner, in round two.
Defending champion Amber Marsh Elliot won the first hole, but was unable to hold on as she lost 1-down to Julie Massa. Massa will face Julie Garner, who won 4 and 3 in the first round.
'I just couldn't get any momentum,' said Marsh Elliot. 'It's disappointing. You always want to do better, and you always want to go far in match play.'
Martha Lang, who won this title in 1988, fell 4 and 3 to Joan Garety.
Andrea Kraus outlasted Mary Jane Hiestand 1-up in 22 holes. Lea Bagwell- Venable and Julie Carmichael were also extended to extra holes as they won in 20 and 19 holes respectively.
The second and third rounds will be played on Monday with the quarterfinal and semifinal rounds on Tuesday. The 18-hole final will be contested on Wednesday.
The Women's Mid-Amateur is one of 13 national championships conducted annually by the United States Golf Association, 10 of which are strictly for amateurs.