Fifteenth seed Learner Tien of the United States held off Paraguayan lucky loser Adolfo Daniel Vallejo 6-3, 5-7, 7-5 in the first round of the Rolex Paris Masters on Tuesday. He will face Frenchman Luca Van Assche in the second round.

Vallejo, who lost in the final round of qualifying, took the place of Stefanos Tsitsipas, who withdrew with a right shoulder injury on Tuesday. The Paraguayan had beaten Tien 6-4, 6-3 in the second round in Madrid in April.

Tien needs to reach at least the third round this week to avoid dropping out of the top 20 for the first time since his top-20 debut in May, according to the ATP. The 20-year-old reached the second round in Paris last year.

The American won his first ATP title in Metz in 2025 and reached the semi-finals in Montreal this season.

Van Assche beat Mariano Navone 6-3, 7-5 on Monday for his first win in Paris.

Rolex Paris Masters 2026 first-round results

Lorenzo Musetti d. Hubert Hurkacz 7-6 (3), 7-6 (10)
Luca Van Assche d. Mariano Navone 6-3, 7-5
Learner Tien (15) d. Adolfo Daniel Vallejo (LL) 6-3, 5-7, 7-5
Novak Djokovic (10) vs Valentin Vacherot (Tuesday)
Rinky Hijikata (Q) d. Luciano Darderi 6-2, 6-2
Tomas Martin Etcheverry d. Andrey Rublev 6-4, 6-7 (4), 7-6 (3)
Cameron Norrie d. Matteo Arnaldi 6-4, 1-6, 6-3
Mattia Bellucci (Q) d. Lorenzo Sonego (Q) 6-4, 6-3
Arthur Rinderknech d. Francisco Cerundolo (16) 3-6, 7-6 (2), 2-0 ret.
Tommy Paul (12) vs Holger Rune (PR) (Tuesday)
Daniel Merida d. Sebastian Baez (LL) 6-4, 6-2
Quentin Halys d. Arthur Fery 7-6 (6), 7-5
Jan-Lennard Struff (SE) vs Arthur Gea (WC) (Tuesday)
Casper Ruud d. Juan Manuel Cerundolo (Q) 6-3, 6-2
Rafael Jodar (9) d. Alejandro Tabilo 6-2, 6-3
Nuno Borges (LL) d. Moise Kouame (WC) 6-3, 6-1
Karen Khachanov d. Denis Shapovalov 6-3, 6-7 (6), 1-4 ret.
Ignacio Buse d. Zizou Bergs 6-2, 6-4
Tomas Machac (Q) d. Kyrian Jacquet (WC) 7-6 (7), 6-1
Alex Molcan (Q) d. Titouan Droguet (WC) 4-6, 6-4, 6-4
Benjamin Bonzi (Q) vs Taylor Fritz (11) (Tuesday)
Brandon Nakashima (14) vs Matteo Berrettini (Tuesday)
Ugo Humbert d. Botic van de Zandschulp 7-6 (5), 6-7 (9), 6-3
Alex Michelsen vs Jiri Lehecka (Tuesday)