TennisEdge's AI model finds no betting value in H. Guo vs S. Costoulas (French Open on 2026-05-21) — the market is efficient, with S. Costoulas favoured at 1.58.
Independent estimates of who wins, each from a different method. The blend is what the bot prices against the market.
| Method | H. Guo | S. Costoulas |
|---|---|---|
| Elo ratings-based, surface-weighted |
37.1% | 62.9% |
| Machine learning 29-feature gradient-boosted model |
31.0% | 69.0% |
| Serve / return point-by-point simulation |
44.4% | 55.6% |
| Blend what the bot actually prices off |
37.5% | 62.5% |
| Market implied de-vigged from the opening odds |
40.9% | 59.1% |
We publish how well these score against the closing market, including where they lose: how accurate are tennis predictions?
| Player | Surface | Elo | Record | Matches |
|---|---|---|---|---|
| H. Guo | hard | 1641 | 80–48 | 128 |
| S. Costoulas | hard | 1570 | 131–79 | 210 |
Our own ratings, computed from match results since 2018. Players with fewer than 5 rated matches are omitted rather than shown at a provisional starting value. Last updated Aug. 1, 2026.
H. Guo leads 1–0 over 1 meeting. Full record.
| Date | Event | Surface | Winner | Score |
|---|---|---|---|---|
| May 21, 2026 | French Open | clay | H. Guo | 2 - 0 |
| L | K. Day | 0 - 2 | Aug. 1, 2026 |
| L | Xiy. Wang | 2 - 0 | June 23, 2026 |
| W | E. Jacquemot | 1 - 2 | June 7, 2026 |
| L | M. Inglis | 1 - 2 | June 7, 2026 |
| L | M. Kessler | 1 - 2 | May 25, 2026 |
| L | G. Knutson | 2 - 0 | Aug. 4, 2026 |
| L | M. Inglis | 0 - 2 | July 29, 2026 |
| W | L. Cabrera | 0 - 2 | July 29, 2026 |
| L | A. Aksu | 2 - 1 | July 20, 2026 |
| W | A. Aksu | 2 - 0 | July 19, 2026 |
All May 21, 2026 results & picks →
Math-only prediction: no LLM calls used