Date-Krumm, who had rallied from a set and a break down to beat Heather Watson in the first round, was sharp from start to finish this time against Kirilenko, winning six games in a row at one point - taking her from 4-3 in the first set to 63 40 - and eventually cruising through in straight sets, 63 61.
"Maria is a very strong player, but I felt she had some kind of problem today," Date-Krumm said. "She didn't run everywhere like she usually does, so I think she had something wrong with her. She wasn't putting as much pressure on me today, so I just had to control myself and my game until the end."
Date-Krumm won the press room over after she was asked about her secrets to match recovery.
"I drink a lot, eat a lot, and eat a lot of Korean food!" the Japanese veteran said.
Date-Krumm's win over the No.19-ranked Kirilenko was her 10th win over a Top 20 player since coming back to the tour in 2008 - she had eight Top 20 wins during a re-breakthrough 2010 season (Virginie Razzano, Nadia Petrova, Dinara Safina, Anastasia Pavlyuchenkova, Maria Sharapova, Sam Stosur, Shahar Peer and Li Na) and got her ninth earlier this year (another one against Petrova).
"I had never played her before, and she started very well - the first few games were long and tight," Radwanska said. "But after a few games I knew what I had to do to win the match, and I started to play more aggressive from there. I started the second set very well and that helped me in the end."
The other match of the day saw South Korean wildcard Jang Su Jeong follow her first round upset of No.4 seed Klara Zakopalova with a come-from-behind 16 64 61 win over Tunisian qualifier Ons Jabeur.
"I was very nervous in the first set, but in the middle of the second set my coach came and helped me, encouraged me, and I changed my mentality," Jang said. "My goal for this tournament was just to get one win, but now I have two, so I'm very happy. I have to thank the crowd for all their support."
Jang is the first Korean in a WTA quarterfinal since Cho Yoon Jeong was a finalist at Canberra in 2006.
Radwanska, Date-Krumm and Jang will all play their quarterfinal matches on Friday. The other five players in the quarterfinals all won their second round matches on Wednesday (read about those here).