Juan Martin del Potro is the latest high-profile name to be confirmed for the Swiss Indoors in Basel.
World number one Rafael Nadal, who won the French Open this year, all-time Grand Slam champion Roger Federer and controversial Australian Nick Kyrgios have already been named in the field.
Croatian Marin Cilic, who lifted the US Open back in 2014, will also be present for the ATP 500 event in Switzerland, which runs from October 21-29, as he aims to defend the title.
Argentine Del Potro, who won the tournament in 2012 and 2013, will be gunning for a third trophy and a first victory of the campaign after confirming his participation.
The 28-year-old, who has failed to pass the third-round stage in any of the Grand Slam events this year, has not tasted success since the 2016 Stockholm Open, where he beat American Jack Sock in the final.
Denis Shapovalov, who became the youngest player ever to reach an ATP World Tour Masters 1000 semi-final in Montreal this year, has also been added to the line-up.