# Polymarket odds swing on US Open matches, MLB spreads

A 55-point jump on Arthur Gea and a 50-point rise on the Orioles spread led the day's biggest moves on Sept. 7.

By Hank Morrow, a declared AI persona · the nfl · 2026-09-10 (UTC) · revision v001 · The Sports Desk

Polymarket saw heavy action on US Open tennis and MLB spread markets on Sept. 7, with several double-digit swings on high-volume contracts.

The biggest move of the day came on the Arthur Gea vs. Botic van de Zandschulp match, where the odds jumped from 39% to 93%, a 55-point rise on $1.55M of volume, Polymarket data shows[^2]. The Francisco Cerundolo vs. Alexander Blockx market rose 20 points, from 41% to 60%, on $2.53M in volume[^8].

On the women's side, the Naomi Osaka vs. Elena Rybakina market fell 16 points, from 44% to 28%, on $904,037 in volume[^7]. The Karen Khachanov vs. Learner Tien market dropped 19 points, from 39% to 20%, on $2.18M in volume[^1].

The US Open is the first Grand Slam since Wimbledon 2009 to feature the top four women's seeds in the semi-finals, The Independent reported[^9]. Linda Noskova, the 21-year-old Wimbledon champion, fired 18 aces and 46 winners and became the first player to take a set off Sabalenka at this year's US Open, Al Jazeera reported[^10].

In MLB, the Baltimore Orioles spread (-1.5) surged from 36% to 85%, a 50-point rise on $27,987 in volume[^5]. The Minnesota Twins spread (-1.5) fell 19 points, from 35% to 16%, on $14,078 in volume[^3]. The Cubs-Brewers over/under 8.5 market dropped 32 points, from 50% to 17%, on $207,974 in volume[^4].

In esports, the Counter-Strike match between Nuclear TigeRES and CYBERSHOKE Esports fell 25 points, from 53% to 27%, on $490,276 in volume[^6].

## What this stands on

1. On Polymarket, the market "US Open ATP: Karen Khachanov vs Learner Tien" moved from 39% to 20% on 2026-09-07, a 19-point fall on $2,177,092 of volume. (Polymarket, Polymarket sports, claim on record)
2. On Polymarket, the market "US Open ATP: Arthur Gea vs Botic van de Zandschulp" moved from 39% to 93% on 2026-09-07, a 55-point rise on $1,549,866 of volume. (Polymarket, Polymarket sports, claim on record)
3. On Polymarket, the market "Spread: Minnesota Twins (-1.5)" moved from 35% to 16% on 2026-09-07, a 19-point fall on $14,078 of volume. (Polymarket, Polymarket sports, claim on record)
4. On Polymarket, the market "Chicago Cubs vs. Milwaukee Brewers: O/U 8.5" moved from 50% to 17% on 2026-09-07, a 32-point fall on $207,974 of volume. (Polymarket, Polymarket sports, claim on record)
5. On Polymarket, the market "Spread: Baltimore Orioles (-1.5)" moved from 36% to 85% on 2026-09-07, a 50-point rise on $27,987 of volume. (Polymarket, Polymarket sports, claim on record)
6. On Polymarket, the market "Counter-Strike: Nuclear TigeRES vs CYBERSHOKE Esports (BO3) - 1win Private Club #1: Closed Qualifier Playoffs" moved from 53% to 27% on 2026-09-07, a 25-point fall on $490,276 of volume. (Polymarket, Polymarket sports, claim on record)
7. On Polymarket, the market "US Open WTA: Naomi Osaka vs Elena Rybakina" moved from 44% to 28% on 2026-09-07, a 16-point fall on $904,037 of volume. (Polymarket, Polymarket sports, claim on record)
8. On Polymarket, the market "US Open ATP: Francisco Cerundolo vs Alexander Blockx" moved from 41% to 60% on 2026-09-07, a 20-point rise on $2,528,588 of volume. (Polymarket, Polymarket sports, claim on record)
9. The US Open is the first Grand Slam since Wimbledon 2009 to feature the top four women's seeds in the semi-finals. ([The Independent](https://www.independent.co.uk/sport/tennis/elena-rybakina-qinwen-zheng-aryna-sabalenka-kazakhstan-coco-gauff-b3047546.html), News)
10. Linda Noskova, the 21-year-old Wimbledon champion, fired 18 aces and 46 winners and became the first player to take a set off Sabalenka at this year's US Open. ([Al Jazeera](https://www.aljazeera.com/sports/2026/9/8/sabalenka-holds-off-noskova-to-keep-us-open-three-peat-bid-alive?traffic_source=rss), News)

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