John Degenkolb claims maiden stage win at the Tour de France

John Degenkolb won a chaotic stage nine of the Tour de France over the cobbles to Roubaix, as race leader Greg Van Avermaet extended his overall advantage.

But there was drama in behind, with Richie Porte forced to abandon the race after an early fall, and four-time winner Chris Froome, Mikel Landa and Rigoberto Uran also hitting the deck.

And Romain Bardet suffered a string of mechanical issues, as the general classification contenders endured a testing day on the cobbles.

Froome recovered to finish in a much-reduced peloton alongside Team Sky team-mate Geraint Thomas, 27 seconds behind the leaders.

Meanwhile, it was a first career Tour stage win for Trek-Segafredo's Degenkolb, with the German able to hold off Van Avermaet and Quick-Step Floors' Yves Lampaert as they sprinted to the line.

Degenkolb won the Paris-Roubaix classic, which covers much of the same course, in 2015.

The trio had broken clear with a little under 20km to go, and second place was enough for Van Avermaet to extend his lead in yellow to 43 seconds over Thomas, going into Monday's rest day.

At the end of a tense day, Van Avermaet topped the general classification from Thomas, with Quick-Step Floors' Philippe Gilbert and Bob Jungels next in line, just a handful of seconds behind the Welshman.

Movistar's Alejandro Valverde is fifth, 91 seconds down, with Froome and Mitchelton-Scott's Adam Yates eighth and ninth respectively, one minute and 42 seconds off yellow.

Although Van Avermaet retains yellow, it was a disappointing day overall for BMC.

While Porte headed for hospital, their other contender Tejay Van Garderen - who started the day just nine seconds off yellow - got himself caught up in crashes and conceded more than five minutes, to effectively rule himself out of contention.

The riders now face a long transfer to Annecy, but have Monday's rest day to recover before the race moves into the Alps and the battle for overall victory hots up.

Stage Nine result:

1. John Degenkolb (GER) Trek - Segafredo 3:24:26

2. Greg Van Avermaet (BEL) BMC Racing Team same time

3. Yves Lampaert (BEL) Quick-Step Floors same time

4. Philippe Gilbert (BEL) Quick-Step Floors +19"

5. Peter Sagan (SVK) BORA - hansgrohe same time

6. Jasper Stuyven (BEL) Trek - Segafredo same time

7. Bob Jungels (LUX) Quick-Step Floors same time

8. Andre Greipel (GER) Lotto - Soudal +27"

9. Edvald Boasson Hagen (NOR) Team Dimension Data same time

10. Timothy Dupont (BEL) Wanty - Groupe Gobert same time

Overall leaders:

1. Greg Van Avermaet (BEL) BMC Racing Team 36:07:17

2. Geraint Thomas (GBR) Team Sky +43"

3. Philippe Gilbert (BEL) Quick-Step Floors +44"

4. Bob Jungels (LUX) Quick-Step Floors +50"

5. Alejandro Valverde (ESP) Movistar Team +1:31"

6. Rafal Majka (POL) BORA - hansgrohe +1:32"

7. Jakob Fuglsang (DEN) Astana Pro Team +1:33"

8. Chris Froome (GBR) Team Sky +1:42"

9. Adam Yates (GBR) Mitchelton - Scott same time

10. Mikel Landa (ESP) Movistar Team same time