2015 season

Landa (left) with Fabio Aru and Steven Kruijswijk at the 2015 Giro d'Italia

In 2015, Landa attacked from a breakaway on the final climb of the day to win the fifth stage of his home race, the Tour of the Basque Country.^[10] Landa rode the Giro d'Italia, again initially as a domestique for Aru. On Stage 8, the second mountain top finish of the race to Campitello Matese, Landa finished second after following an attack by Aru, and then unsuccessfully chasing after leader Beñat Intxausti (Movistar Team) in an attempt to win the stage. By doing so Landa rose to fifth place overall, 42 seconds down on leader Alberto Contador (Tinkoff–Saxo).^[11] Landa rose to third overall on Stage 10, when Richie Porte (Team Sky) was given a time penalty for accepting a wheel change from Orica–GreenEDGE rider Simon Clarke.^[12] On Stage 14, a 59.4-kilometre (36.9-mile) individual time trial, Landa was caught on the road by Contador, losing over three minutes to him, and dropped to seventh overall, 4 minutes 55 seconds back. However, the next day, Landa won the mountainous Stage 15 after attacking Contador on the final climb to Madonna di Campiglio, and proving stronger than Aru, who he finished six seconds ahead of.^[13]

Stage 16 was the queen stage of the race with five Italian Alpine peaks, including the Tonale Pass, the Mortirolo Pass and a mountain finish to Aprica. On the first of two climbs to Aprica, Contador suffered a mechanical problem, after which Team Katusha and Astana immediately pressed on the pace at the front, sparking a bit of controversy over respect and fair play.^[14] After a long chase Contador eventually caught up with Landa, Aru and Steven Kruijswijk (LottoNL–Jumbo) on the Mortirolo after being 52 seconds down at the start of the climb. Contador then counter-attacked, with Landa proving stronger than Aru, who was unable to follow the move. Landa rode away on the final ascent to Aprica, winning his second stage in a row by 38 seconds over Kruijswijk and Contador. Aru finished 2 minutes and 51 seconds behind, and thus Landa moved ahead of his teammate to second overall.^[15] However, on Stage 19 it was Aru who proved the stronger of the two, attacking on the final climb to Breuil-Cervinia and taking 1 minute and 18 seconds on Contador and Landa, who did not respond to his move. On Stage 20, the last mountain stage, Landa attacked on the Colle delle Finestre, taking the Cima Coppi for crossing the highest point of the race in the lead as he crossed the summit with Ilnur Zakarin (Team Katusha), a minute ahead of Aru and a minute and a half ahead of Contador. However, Landa waited for Aru on the descent, and the pair were unable to take sufficient time from Contador on the remainder of the stage, before Aru attacked on the final climb to Sestriere to win the stage. Although Contador lost two and a half minutes, he kept the maglia rosa with a lead of 2' 02" over Aru to win the Giro, with Landa finishing third overall 3 minutes 14 seconds back.^[16]

Landa rode the Vuelta a España again in support of Aru, after Astana's other leader Vincenzo Nibali was disqualified on the second stage for holding onto a team car. Landa won the mountainous stage 11 from Andorra la Vella to Cortals d'Encamp from the breakaway, ignoring team orders to drop back and assist Aru.^[17] However, Landa did work for Aru during the rest of the race as Aru traded the race lead with Tom Dumoulin (Team Giant–Alpecin), and played a key role in the decisive move on stage 20 when he and Aru dropped Dumoulin on the penultimate climb before being joined by teammates from the breakaway to ride away from Dumoulin, who lost over three minutes and thus the Vuelta to Aru.

2016 season

After missing several early season races through illness, Landa made his first appearance for Team Sky at the Settimana Internazionale di Coppi e Bartali, finishing 11th overall.^[19] Landa then rode his home race, the Tour of the Basque Country, where he won the second stage to take the race lead.^[20] Landa led Team Sky at the Giro del Trentino in his last warm up race before the Giro d'Italia. He won Stage 2 to take the race lead, and successfully defended it on the following two stages despite attacks from Astana duo Tanel Kangert and Jakob Fuglsang to take overall victory by a single second over Kangert.^[21] Landa abandoned the Giro d'Italia part-way through Stage 10 after being hampered by illness overnight and being diagnosed with viral gastroenteritis. This came just a day after he had impressed in the Stage 9 individual time trial, after which he was sitting in 8th place overall.^[22] Landa was named in the start list for the Tour de France.^[23] He helped Chris Froome win the race for a third time by acting as a mountain domestique.

2017 season

Landa at the 2017 Giro d'Italia

In January 2017 it was announced that Landa would share leadership with Geraint Thomas at the Giro d'Italia.^[24] However, on stage 9, as the peloton approached the final climb of the day to Blockhaus, Wilco Kelderman of Team Sunweb collided with a stationary police motorcycle, that caused him to swerve to his right into the Sky riders, which resulted in Landa and the majority of his team mates being brought down.^[25] Landa was able to remount and continue, but he finished almost 27 minutes down on the stage winner, Nairo Quintana.^[26] With his hopes of a high overall finish in the race over, Landa rode aggressively in several breakaways in the mountains. He finished third on Stage 14 and won his second Cima Coppi on Stage 16, beating Igor Antón (Team Dimension Data) to the summit of the Stelvio Pass.^[27] Later in the stage he was in the breakaway group at the front of the race and with about 25 kilometres (16 miles) to go in the stage he dropped his breakaway companions Jan Hirt and Steven Kruijswijk. He was caught by Vincenzo Nibali on the descent from the final climb and the two remained clear to the finish in Bormio; Nibali out-sprinted Landa for the stage victory, but Landa took the lead of the mountains classification.^[28] Landa finished second again on stage 18, losing by a bike length to Tejay van Garderen,^[29][30] but won the following stage to the ski resort of Piancavallo, securing an unassailable lead in the mountains classification.^[31]

Landa was named in the start list for the Tour de France, initially as a mountain domestique for Chris Froome. On Stage 12 which finished with a short steep climb to Peyragudes, Landa finished fourth, five seconds behind stage winner Romain Bardet whilst Froome came seventh, 22 seconds down on Bardet.^[32] On Stage 13, Landa was part of a four man breakaway with Warren Barguil, Quintana and Alberto Contador. Barguil won the stage, with the quartet finishing 1:39 ahead of the other overall contenders.^[33] On Stage 15, Froome suffered a broken spoke on the Peyra Taillade climb, but with some assistance from Landa and other teammates, he was able to chase back up to the group before the summit.^[34][35] Landa ultimately placed fourth behind Froome, Rigoberto Urán and Bardet, finishing just 1 second behind Bardet in third.^[36]

On 29 July, one week after the end of the Tour de France, Landa placed fifth in a five-rider group sprint in the Clásica de San Sebastián, which was won by teammate Michał Kwiatkowski.^[37] The following week, Landa took overall victory at the Vuelta a Burgos, as well as winning two stages and the points and mountains classifications.