Mollema was able to revel in his first stage win, after timing his attack perfectly on the descent of the Col de Peyra Taillade, but Lotto Soudal's Tim Wellens was an early casualty on Sunday's stage as he abandoned.
After Monday's second rest day and a likely straightforward stage on Tuesday with a bunch sprint finish, Wednesday sees the Tour head into the Alps for the final mountain showdown of this year's race.
After a fast wheel change, the race leader went to work with Mikel Nieve and Sergio Henao to peg back the 30-second deficit to the other favourites on the steep ascent.
The 26-year-old climbing specialist finished runner-up to Froome last year and wants to move one step higher on the podium.
"One minute you're in there and ripping it and next minute you're out of the top 10 and people are wondering what's going on", he said, having fallen down to 12th place at the Tour de France after stage 15.
"All the the guys helped me as much as they could, and I'm hugely grateful". Just before the climb I had a problem with my back wheel, it was damaged. The yellow jersey, distanced 45 seconds by his direct opponents, and managed to regain his place in the group of the favorites before the summit of the pass.
Four categorised climbs, including two first category ones, will encourage strong all-rounders to take off in the breakaway, but it may also give the overall contenders a chance to do battle and create gaps.
Landa is now up to fifth overall, just 1 minute 9 seconds behind Astana's Aru, who leads Froome by 6 seconds.
"It's a dream come true", said Matthews, whose Team Sunweb claimed their second stage wins in as many days after Frenchman Warren Barguil claimed stage 13 on Bastille Day. Mikel Landa (Spain / Team Sky) +1:17'; 7. My wheel wasn't straight anymore so I think it was a broken spoke but I'm not sure.
Team Sky's yellow jersey Chris Froome chats to white jersey Simon Yates from Orica-Scott before the start of stage 15 in Laissac-Severac l'Eglise.
The Monaco-based rider, 32, added: "It's all thanks to my team-mates that I got the jersey back and special thanks to Michal Kwiatkowski who was superb all day". His rivals are now smelling blood, especially with two other big names - Spain's Alberto Contador and Colombian Nairo Quintana out of contention.
It's really fantastic. I'm so happy to win a stage at the Tour de France. "There were attacks, people tried to attack me several times but I responded every time". I had a sore throat, a headache, a bit of the sweats.