(CNN) -- Chris Froome retained the yellow jersey on a day of toil and trouble as Ireland's Dan Martin won the ninth stage of the Tour de France. 

Sky Team rider Froome, who has a one minute and 25 second lead over his closest challenger, was forced to battle on his own as his teammates failed to give him adequate protection. 

Richie Porte lost his grip on second place overall after finishing more than 17 minutes adrift, while Vasili Kiryienka was swept up by a broom wagon and is unlikely to feature in the remainder of the Tour. 

There was also misery for Peter Kennaugh, who suffered bruising after falling from his bike -- an incident which left Froome wide open to attack on all fronts. 

"This was one of the hardest days I have ever had on the bike," Froome told reporters. 

"I had no-one else with me. I am really happy I have come through today. I was completely on my own, I had (sporting director) Nicolas Portal in the car telling me not to worry." 

Martin, the nephew of great Irish cyclist Stephen Roche, won the long descent to Bagneres-de-Bigorre with Froome following home 20 seconds later in a pack which included rivals Alejandro Valverde and Alberto Contador. 

Team Sky principal Dave Brailsford revealed his surprise at seeing his team struggle with Porte's failure particularly difficult for him to comprehend. 

"That was a bit of a surprise, it is not often we've seen Richie have a day like that," Brailsford said. 
What race is this about?
What stage of the tour?
Who is Martin the nephew of?
Who kept the yellow jersey?
Did Froome also win the ninth stage?
Who won the ninth stage?
Did anyone fall?
who fell?
Was he injured?
Who finished over 17 minutes back?
What team does Froome ride for?
how big is Froome's lead?
Where is Martin from?
Was Froome riding with others?
Who won the descent?
Tour de France.
Tour de France. 
ninth
 ninth
great Irish cyclist Stephen Roche,
great Irish cyclist Stephen Roche,
Chris Froome
Chris Froome
no
Dan Martin won
Dan Martin
Dan Martin
yes
Peter Kennaugh,
Peter Kennaugh
Peter Kennaugh
suffered bruising
suffered bruising
Richie Porte
Richie Porte
Sky Team
Sky Team 
one minute and 25 second
 one minute and 25 second
Ireland
Ireland
no
I had no-one else with me
Martin,
Martin,