Explanation: The source material explicitly identifies its primary subject as the singles competition of the 2013 St. Petersburg Open.

Explanation: The source confirms that Ernests Gulbis won the tournament by defeating Guillermo García-López in the final match.

Explanation: Guillermo García-López was the runner-up; he was defeated by the champion, Ernests Gulbis, in the final.

Explanation: The final score was 3–6, 6–4, 6–0, indicating that Ernests Gulbis lost the first set before rallying to win the match and the tournament.

Explanation: Martin Kližan was the defending champion but withdrew from the 2013 tournament before it began and did not participate.

Explanation: Ernests Gulbis of Latvia was the champion, defeating Guillermo García-López in the final match.

Explanation: Guillermo García-López of Spain reached the final but was defeated by Ernests Gulbis, making him the tournament runner-up.

Explanation: Martin Kližan was the defending champion but did not participate in the 2013 tournament, having withdrawn before it started.

Explanation: The main draw for the tournament consisted of 32 players, not 64.

Explanation: The tournament featured eight seeded players who were strategically placed in the draw to prevent them from meeting in early rounds.

Explanation: The designation 'Q' stands for 'Qualifier,' a player who earned their spot in the main draw through a preliminary qualifying tournament.

Explanation: 'WC' stands for 'Wild Card,' an entry granted to a player by tournament organizers, not a 'Walkover'.

Explanation: 'LL' correctly identifies a 'Lucky Loser,' a player who lost in the final qualifying round but entered the main draw due to another player's withdrawal.

Explanation: 'PR' stands for 'Protected Ranking,' which allows a player returning from a long-term injury to use their pre-injury ranking for tournament entry.

Explanation: The 'r' symbol indicates that a player retired mid-match, typically due to injury or illness.

Explanation: The main draw for the tournament consisted of a field of 32 competitors.

Explanation: There were 8 seeded players in the main draw, who were separated to prevent them from playing each other in the early rounds.

Explanation: 'Q' stands for 'Qualifier,' indicating a player who earned a spot in the main draw by winning matches in a preliminary qualifying tournament.

Explanation: 'WC' stands for 'Wild Card,' an entry granted to a player by tournament organizers who would not otherwise qualify based on ranking.

Explanation: 'LL' stands for 'Lucky Loser,' a player who loses in the final qualifying round but gains entry into the main draw when another player withdraws.

Explanation: 'PR' stands for 'Protected Ranking,' which allows a player who has been sidelined by a long-term injury to use their pre-injury ranking for tournament entry.

Explanation: The symbol 'r' indicates that a player 'Retired' from a match before it was completed, usually due to injury.

Explanation: Of the top four seeds, only Dmitry Tursunov (4th seed) reached the quarterfinals. The other three were eliminated in the first or second rounds.

Explanation: As the 6th seed, Ernests Gulbis was part of the 5th-8th seed group and went on to win the entire tournament.

Explanation: Fernando Verdasco, the fifth seed, was eliminated in the first round of the tournament.

Explanation: The source confirms these were the correct pairings for the two semifinal matches.

Explanation: Ernests Gulbis defeated Michał Przysiężny in straight sets (6–3, 6–3) to advance to the final.

Explanation: The source confirms that Guillermo García-López won his semifinal match against João Sousa with a dominant score of 6–1, 6–1.

Explanation: There were three unseeded semifinalists: Michał Przysiężny, João Sousa, and Guillermo García-López. Ernests Gulbis was the only seeded player in the semifinals.

Explanation: As an unseeded player from the bottom half of the draw, Guillermo García-López successfully reached the tournament final.

Explanation: Fabio Fognini, the first seed, retired from his second-round match against Michał Przysiężny; he did not complete the match.

Explanation: The source confirms that fifth-seeded Fernando Verdasco lost his first-round match to Sergiy Stakhovsky with a score of 3–6, 4–6.

Explanation: Mikhail Youzhny, the second seed, was defeated by Guillermo García-López in the second round and was therefore eliminated from the tournament.

Explanation: Dmitry Tursunov (4th seed) was the only top-four seed to reach the quarterfinals. Fognini (1st) and Youzhny (2nd) lost in the second round, and Tipsarević (3rd) lost in the first round.

Explanation: Ernests Gulbis, the 6th seed, was the player from this group who went on to win the entire tournament.

Explanation: One semifinal featured João Sousa vs. Guillermo García-López. The other featured Michał Przysiężny vs. Ernests Gulbis. The finalists, Gulbis and García-López, did not play each other until the final.

Explanation: Ernests Gulbis defeated Michał Przysiężny in straight sets, 6–3, 6–3, to advance to the tournament final.

Explanation: Guillermo García-López advanced to the final with a dominant 6–1, 6–1 victory over João Sousa.

Explanation: Michał Przysiężny was the unseeded player from the top half of the draw who advanced to the semifinals, notably defeating the first seed along the way.

Explanation: Guillermo García-López was the unseeded player from the bottom half of the draw who reached the semifinals and then won that match to advance to the final.

Explanation: Fabio Fognini, the top seed, retired from his second-round match against Michał Przysiężny, resulting in his elimination from the tournament.

Explanation: Fifth-seeded Fernando Verdasco was defeated in the first round by Sergiy Stakhovsky of Ukraine.

Explanation: Mikhail Youzhny, the second seed, was eliminated in the second round after being defeated by Guillermo García-López.

Explanation: These four players successfully navigated the qualifying rounds to earn a spot in the main draw of the tournament.

Explanation: Konstantin Kravchuk, the top seed in qualifying, successfully qualified for the main draw.

Explanation: The source confirms that eighth-seeded Vladimir Ivanov lost his first-round qualifying match to Dominic Inglot.

Explanation: Konstantin Kravchuk defeated Alexander Bury in the final qualifying round. Mikhail Biryukov also qualified, but by defeating Valery Rudnev.

Explanation: The source confirms that Samuel Groth won his final qualifying match against Victor Baluda to advance to the main draw.

Explanation: Dominic Inglot defeated Alexander Kudryavtsev, the third seed in qualifying, to advance. The top seed was Konstantin Kravchuk, who also qualified.

Explanation: Konstantin Kravchuk was one of the four players who successfully advanced through the qualifying rounds to enter the main draw. The other options were defeated in the final qualifying round.

Explanation: Both Konstantin Kravchuk (1st seed) and Samuel Groth (2nd seed) successfully won their qualifying matches and advanced to the main draw.

Explanation: Vladimir Ivanov of Estonia, the eighth seed in the qualifying draw, was defeated in his first-round match by Dominic Inglot.

Explanation: Konstantin Kravchuk, the top seed in qualifying, defeated Alexander Bury of Belarus in the final qualifying round to secure his spot.

Explanation: Samuel Groth, the second seed in qualifying, defeated Victor Baluda of Russia in his final qualifying match.

Explanation: Dominic Inglot defeated Alexander Kudryavtsev, the third seed in qualifying, to earn his place in the main draw.

Explanation: Mikhail Biryukov (6th seed) defeated Valery Rudnev (4th seed) in the final qualifying round to advance to the main draw.