In 2015, Charleston marked a 17-year-old Naomi Osaka's Tour-level clay debut; the Japanese player defeated Paula Kania in qualifying before falling to Danka Kovinic. Today, the Indian Wells champion takes on an opponent against whom she has lost her only previous encounter in Jennifer Brady. The American won 6-4, 6-4 in the first round of the ITF $50,000 event in New Braunfels, Texas back in 2014.
Another seed facing a player she has never beaten is No.11 Daria Gavrilova, who is 0-2 against Ons Jabeur in junior and pro competition combined. The Tunisian defeated Gavrilova in the quarterfinals of the Roland Garros girls' event in 2011 en route to winning the title, and then again in the first round of Baku in 2013. However, Jabeur's 2018 record is just 1-8, with her sole win coming over three sets against World No.521 Fatma Al Nabhani in Dubai qualifying.
No.14 seed Alizé Cornet is 2-2 against Kateryna Bondarenko in a rivalry going back over a decade. The Frenchwoman won their first match, in Australian Open qualifying in 2007, and their most recent, in Wuhan qualifying in 2016; but Bondarenko took their sole clay encounter 6-4, 6-1 in the second round of Rome in 2009.
Laura Siegemund and wildcard Bethanie Mattek-Sands are both playing their second tournament back from knee injuries that kept both players out for the second half of 2017. Mattek-Sands' comeback in Miami was ended in the first round by Alizé Cornet; meanwhile, Siegemund chose to return in an ITF $25,000 event in Santa Margherita di Pula in Italy, where she won two matches to reach the quarterfinals before falling to Michaela Honcova.
Two players who slayed seeds in Miami, Zarina Diyas and Christina McHale, face each other in the first round today. Their head-to-head is 1-1: the American won their sole clay encounter via retirement in the 2014 Strasbourg quarterfinals, but Diyas gained her revenge last year in Tokyo, coming from a break down in the deciding set to win their semifinal 6-4, 0-6, 6-3 - and going on to claim her maiden title.
Both of Charleston's 2014 finalists are in action on Day 1 this year. Champion Andrea Petkovic and runner-up Jana Cepelova are now ranked No.99 and No.116 respectively, and neither have progressed beyond the second round here in the past two years.
2016 Australian Open girls' champion Vera Lapko has qualified for her first WTA main draw of 2018 - having fallen in the final qualifying round in her past five tournaments. The Belarusian takes on No.15 seed Mihaela Buzarnescu in a bid to win her first main draw match since her Moscow quarterfinal run last October. Buzarnescu won their only previous match to date, 6-3, 6-2 in the second round of the ITF $60,000 event in Hodmezovasarhely, Hungary last June.
Belgian qualifier Maryna Zanevska is in form, having defeated Viktoria Kuzmova and Marta Kostyuk to win the ITF $60,000 event in Zhuhai three weeks ago. However, she is 0-2 against her first-round opponent, Polona Hercog, having won just five games from the Slovenian across two clay matches in 2013 and 2015.
Last year, Fanny Stollar produced one of Charleston's biggest upsets when she shocked 2017 Indian Wells champion Elena Vesnina in the second round. The 19-year-old Hungarian has not won a WTA main draw match since - but she has come through qualifying here for the second consecutive year.
Stollar's first-round opponent is another qualifier, Francesca di Lorenzo. The 20-year-old American is making her WTA main draw debut; a former Ohio State college player, di Lorenzo was the 2017 NCAA doubles champion alongside Miho Kowase, and won her second ITF $25,000 title in Wesley Chapel, Florida in January.
ORDER OF PLAY (all courts start 10am)
VOLVO CAR STADIUM
Kateryna BONDARENKO (UKR) vs  Alizé CORNET (FRA)
Varvara LEPCHENKO (USA) vs Andrea PETKOVIC (GER)
Jennifer BRADY (USA) vs  Naomi OSAKA (JPN)
Aleksandra KRUNIC (SRB) vs [WC] Bethanie MATTEK-SANDS (USA)
ALTHEA GIBSON CLUB COURT
Christina MCHALE (USA) vs Zarina DIYAS (KAZ)
 Daria GAVRILOVA (AUS) vs Ons JABEUR (TUN)
[Q] Sílvia SOLER-ESPINOSA (ESP) vs Camila GIORGI (ITA)
Johanna LARSSON (SWE) vs [Q] Caroline DOLEHIDE (USA)
Bernarda PERA (USA) vs Jana CEPELOVA (SVK)
 Kiki BERTENS (NED) vs Veronica CEPEDE ROYG (PAR)
[Q] Vera LAPKO (BLR) vs  Mihaela BUZARNESCU (ROU)
 Andreja KLEPAC (SLO) / María José MARTÍNEZ SÁNCHEZ (ESP) vs Alicja ROSOLSKA (POL) / Abigail SPEARS (USA)
Laura SIEGEMUND (GER) vs Natalia VIKHLYANTSEVA (RUS)
[Q] Fanny STOLLAR (HUN) vs [Q] Francesca DI LORENZO (USA)
Not before 2pm
Polona HERCOG (SLO) vs [Q] Maryna ZANEVSKA (BEL)
Tatjana MARIA (GER) / Kristyna PLISKOVA (CZE) vs [WC] Lara ARRUABARRENA (ESP) / Sara ERRANI (ITA)