Melbourne VIC, Australia, 5 May 2016 | Matt Trollope & Leigh Rogers

The respective runs of Sam Stosur and Daria Gavrilova at the Mutua Madrid Open have taken on a special significance.

With the pair reaching the quarterfinals in the Spanish capital, it marks the first time – since the introduction of the tiered tournament system in 1990 – that two Australian women have advanced to the last eight at the highest category of WTA tournament.

And they stand to go even further; both Stosur and Gavrilova – who are on opposite sides of the draw in Madrid – face qualifiers on Wednesday for a shot at the semifinals.

“It’s brilliant … I hope there’s a bit of healthy competition between Sam and Dasha to see who’s able to creep further into the draw,” said Australian Fed Cup captain Alicia Molik.

“I think having someone else who’s having a lot of success in singles at the same event also drives you.

“It’s no surprise they’re having success … it just goes to show their preparation throughout the year.

“It’s a massive opportunity, and how good would it be if that number crept to three or four weekly? That’s the idea and that’s something we’ve got to shoot for because I think when someone around you has a bit of success, it’s really easy to want to be in that same spot, and it’s a driving factor.”

The Madrid Open is one of nine WTA Premier Mandatory/Premier 5 tournaments on the calendar, which are the equivalent of the nine ATP Masters Series events.

In addition to Madrid, these blue-ribbon WTA events are staged in Doha/Dubai, Indian Wells, Miami, Rome, Canada, Cincinnati, Wuhan and Beijing.

Prior to 2009, Premier Mandatory/Premier 5 events were known as Tier I events, a category of tournament introduced in 1990.

In researching this Australian milestone, we did not consider straight Premier-level events – tournaments like Brisbane, Sydney, Charleston, Eastbourne, Stanford and New Haven – as these are the current equivalent of the former Tier II events.

Many tournaments have had their status demoted or promoted over the years. For example, Indian Wells was only made a Tier I event in 1997, while the Volvo Car Open – once known as the Family Circle Cup, held in Hilton Head and subsequently in Charleston – was a Tier I event until 2009, when it was assigned Premier status. Therefore, tournaments have only been considered in the years they were categorised as Tier I.

There exists a small core of events – Miami, Rome and Montreal/Toronto – that have held Tier I/Premier Mandatory/Premier 5 status each year since 1990.

Below is a record of all Australian women who have advanced to at least the quarterfinals of any WTA Tier I/Premier Mandatory/Premier 5 tournament since 1990:

Rachel McQuillan – Miami QF
Nicole Bradtke – German Open QF

Jelena Dokic – Hilton Head QF
Jelena Dokic – Rome QF

Jelena Dokic* – Rome champion

Jelena Dokic* – Montreal SF

Jelena Dokic* – Tokyo [Pan Pacific] QF
Jelena Dokic* – Miami QF
Jelena Dokic* – Charleston QF

Jelena Dokic* – Tokyo [Pan Pacific] SF
Alicia Molik – Zurich champion

Sam Stosur – Tokyo [Pan Pacific] QF
Nicole Pratt – Montreal QF
Sam Stosur – Zurich QF

Sam Stosur – Tokyo [Pan Pacific] QF

Sam Stosur – Miami QF
Sam Stosur – Toronto QF

Sam Stosur – Indian Wells SF
Sam Stosur – Miami QF
Sam Stosur – Madrid QF

Sam Stosur – Rome F
Sam Stosur – Toronto F

Sam Stosur – Doha F
Sam Stosur – Madrid QF
Sam Stosur – Tokyo [Pan Pacific] SF

Sam Stosur – Doha QF
Sam Stosur – Indian Wells QF
Sam Stosur – Rome QF

Casey Dellacqua – Indian Wells QF
Sam Stosur – Beijing SF

Daria Gavrilova** – Rome SF

Sam Stosur – Madrid QF^
Daria Gavrilova – Madrid QF^

*Jelena Dokic represented Yugoslavia/Serbia from 2001-2005
**Daria Gavrilova represented Russia prior to 2015
^still alive in tournament