"del Thortro", by fellow tennis player Roger Federer, adding to a collection of nicknames such as "Delpo", "Tower of Tandil", "Palito" (stick) and "Enano" (midget). This led to a joke in social media with Chris Hemsworth, who plays Thor, and in this joke he demands his hammer back because he claimed to need it for his quests. In the quarterfinals he defeated Roger Federer in four tight sets; his second victory over the Swiss at the US Open, having beaten him in the final in 2009. By doing so he reached his first major semifinal since Wimbledon 2013. His run came to an end in 4 sets, losing to World No. 1 Rafael Nadal. Del Potro began his Asian hard court swing in Beijing, where he lost in straight sets Grigor Dimitrov in the second round, his second loss against the Bulgarian. This was followed by a strong performance at the 2017 Shanghai Masters, where he reached the semifinals of a Masters 1000 event for the first time since 2013 (also in Shanghai), most notably upsetting Alexander Zverev in the third round, his second triumph over a Top 5 ranked opponent after his previous victory over Roger Federer at the 2017 US Open. Del Potro won the first set but eventually lost in the semifinals against Federer, who would go on to win the tournament. Del Potro defended his 2016 Stockholm Open title by defeating Grigor Dimitrov in the finals of the 2017 Stockholm Open. This victory gave Del Potro his 20th ATP career title. He then reached the final of Basel, where he faced Federer and again lost in three sets after winning the first. Del Potro then made it to the quarterfinals of the 2017 Paris Masters, where he was one win away from entering the top 10 and qualifying for the 2017 ATP Finals, which would've been his first time since 2013 participating in the year-end tournament. However, he was defeated in three sets by John Isner and subsequently declined to be chosen as an alternate for the tournament, instead choosing to rest with his family and friends in his native Tandil. Nevertheless, Del Potro won 730 points in a span of three weeks and reached the 11th spot of the ATP rankings. 2018: First Masters, second US Open final, world No. 3, injuries Del Potro started the season at the 2018 ASB Classic in New Zealand,