Victory for Boulter comes as she battles to maintain the British primary rating with Emma Raducanu and Sonay Kartal closing in.
Boulter has been the nation’s main girls’s participant since June 2023, however has dropped down the world rankings in a stop-start season.
Raducanu is as much as forty ninth after reaching the Miami quarter-finals final month, whereas Kartal’s speedy rise has moved her as much as sixtieth.
Each play their Madrid first-round matches on Wednesday.
“I do not really feel any stress in any respect,” Boulter advised BBC Sport earlier than beating Siniakova.
“I am very comfy within the seat that I’m and I do know that each single individual has a distinct journey and my journey just isn’t going to be in comparison with anybody else’s – I am pleased with that.
“I have been the British primary for 2 years, it has been a good whereas now. It is one thing which I am fairly used to.”
After successful one and dropping certainly one of her Billie Jean King Cup singles matches final week on indoor clay within the Netherlands, Boulter went to Alicante – the place her fiance Alex de Minaur has lengthy been based mostly – for a coaching week.
She determined that was the wise possibility – as a substitute of compressing in one other WTA clay-court occasion earlier than Madrid – as she continues to handle a foot damage.
The difficulty has left her solely in a position to play 5 tournaments this season, lacking virtually two months of the WTA Tour between the Australian Open in January and Indian Wells in March.
“I wish to see the ladies going greater and better [in the rankings], however personally I’ve my very own targets and attempt to give attention to these lots,” added Boulter, who secured GB’s place within the Billie Jean King Cup Finals alongside Jodie Burrage within the deciding doubles.
“For me I simply must attempt to keep wholesome. That is that almost all essential factor after which the rating will deal with itself.”
