Question: Which player has had more singles appearances, Casey Dellacqua or Olga Morozova? 

Context paragraphs:
2014 PTT Pattaya Open – Doubles: Kimiko Date-Krumm and Casey Dellacqua were the defending champions, but Dellacqua decided not to participate.  Date-Krumm played alongside Ajla Tomljanović, but lost to Alla Kudryavtseva and Anastasia Rodionova in the quarterfinals.

Ashleigh Barty: Ashleigh Barty (born 24 April 1996) is an Australian professional tennis player and cricketer.  Barty first gained media attention by reaching the doubles final of the 2013 Australian Open, partnered by Casey Dellacqua.  The pair also reached the finals of both Wimbledon and the US Open in 2013, making Barty one of the most successful WTA debutants in history.  In 2017, while again partnering with Dellacqua, Ashleigh finished runner-up at the French Open in the women's doubles which means that she has now made the women's doubles final in each of the four grand slams.  She also won the 2011 Wimbledon Girls' Championships title and has won three WTA doubles titles so far in her career.  In September 2014, she took a break from tennis and switched to cricket in 2015, earning a contract with the Brisbane Heat for the inaugural Women's Big Bash League.  In February 2016 she resumed her career in tennis.

1974 Wimbledon Championships – Women's Singles: Chris Evert defeated Olga Morozova 6–0, 6–4 in the final to win the Ladies' Singles tennis title at the 1974 Wimbledon Championships.

2016 Mutua Madrid Open – Women's Doubles: Casey Dellacqua and Yaroslava Shvedova were the defending champions, but Dellacqua chose not to participate this year as she welcomed her second child.  Shvedova played alongside Tímea Babos, but lost in the quarterfinals to Caroline Garcia and Kristina Mladenovic. <br>

Olga Morozova: Olga Vasilyevna Morozova (Russian: Ольга Васильевна Морозова ) (born 22 February 1949) is a retired female tennis player who competed for the Soviet Union.  She was the runner up in singles at the 1974 French Open and 1974 Wimbledon Championships.

2013 Aegon Trophy – Women's Doubles: Eleni Daniilidou and Casey Dellacqua are the defending champions, having won the event in 2012.  Dellacqua chose not to defend her title; Daniilidou partnered up with Coco Vandeweghe, but they lost in the quarterfinals.

Casey Dellacqua career statistics: This is a list of the main career statistics of professional Australian tennis player, Casey Dellacqua.  To date, Dellacqua has won eight career doubles titles: one grand slam mixed doubles title with Scott Lipsky at the 2011 French Open and seven WTA doubles titles including one Premier Mandatory doubles title with Yaroslava Shvedova at the 2015 Mutua Madrid Open.  Other highlights of Dellacqua's career include reaching the doubles finals of all four grand slams; a quarterfinal finish in singles at the 2014 BNP Paribas Open and fourth round appearances at the 2008 Australian Open and 2014 Australian Open and US Open respectively.  Dellacqua achieved a career high singles ranking of World No. 26 on September 29, 2014 and later achieved a career high doubles ranking of World No. 3 on February 1, 2016.

1974 French Open – Women's Singles: Reigning champion Margaret Court did not defend her title.  Chris Evert defeated Olga Morozova 6–1, 6–2 in the final to win the Women's Singles tennis title at the 1974 French Open.

Casey Dellacqua: Casey Dellacqua (born 11 February 1985) is an Australian professional tennis player of Italian and Irish descent.  Dellacqua's best singles results to date have been semifinal appearances at the 2012 Texas Tennis Open and 2014 Aegon Classic, a quarterfinal finish at the 2014 BNP Paribas Open and fourth round appearances at the 2008 Australian Open, 2014 Australian Open and the 2014 US Open.

2012 French Open – Mixed Doubles: Casey Dellacqua and Scott Lipsky were the defending champions.  Dellacqua chose not to participate this year while Lipsky partnered with Vladimíra Uhlířová, but they were defeated in the first round by Virginie Razzano and Nicolas Devilder. <br>

Supporting paragraphs: Casey Dellacqua Olga Morozova
Answer: Casey Dellacqua