The Arizona Diamondbacks look to complete the sweep this afternoon against the San Francisco Giants, with first pitch scheduled for 3:40 p.m. ET at Chase Field.
My Giants vs. Diamondbacks predictions are targeting Arizona to get the job done in the series finale, with the improving Merrill Kelly taking the hill.
Read more in my MLB picks for Wednesday, May 20.
Who will win Giants vs Diamondbacks today: Diamondbacks moneyline (-127)
The Arizona Diamondbacks have looked solid in this series, winning the opener 12-2 before a 5-3 victory on Tuesday evening. The D-Backs own a 14-9 record at home, and they've gone 5-1 across the last six meetings with the San Francisco Giants.
Merrill Kelly takes the mound for the hosts, and while his 5.91 ERA is concerning, he's been better lately. The right-hander has only allowed two earned runs across his previous two starts, and Kelly even threw a complete-game shutout last week against the Colorado Rockies.
On the other side, Tyler Mahle owns a 1-5 record and 5.59 ERA, and he's given up nine earned runs across his last two outings. Also, Mahle has an alarming 8.38 ERA on the road.
COVERS INTEL: Mahle isn't fooling anyone, with chase and whiff rates that rank in the 25th and 26th percentiles, respectively. 
Giants vs Diamondbacks Over/Under pick: Under 8.5 (+105)
I don't expect either starter to be completely lights out, but I also don't see the rubber match being high-scoring. Five of their last seven meetings have cashed the Under, and we saw only eight runs scored on Tuesday.
Mahle is prone to giving up runs, and the D-Backs offense is rolling, ranking ninth in runs scored. Kelly is starting to find his best after a shaky start to the campaign, and the Giants are 30th in runs scored and 27th in both wRC+ and home runs.
You'll see another Arizona-heavy offensive performance here, similar to the rest of this series. Both bullpens, which have pitched well lately, will hold it down after the starters exit.
- ML/RL bets: 12-11 +2.26 units
- Over/Under bets: 14-9, +3.16 units
Giants vs Diamondbacks odds
- Moneyline: Giants +113 | Diamondbacks -136
- Run line: Giants +1.5 (-186) | Diamondbacks -1.5 (+153)
- Over/Under: Over 9 (+100) | Under 9 (-120)
Giants vs Diamondbacks trend
The Arizona Diamondbacks have hit the Moneyline in 31 of their last 50 games at home (+10.50 Units / 17% ROI). Find more MLB betting trends for Giants vs. Diamondbacks.
How to watch Giants vs Diamondbacks and game info
| Location | Chase Field, Phoenix, AZ |
| Date | Wednesday, May 20, 2026 |
| First pitch | 3:40 p.m. ET |
| TV | NBC Sports Bay Area, Diamondbacks.TV |
| Giants starting pitcher | Tyler Mahle (1-5, 5.59 ERA) |
| Diamondbacks starting pitcher | Merrill Kelly (3-3, 5.91 ERA) |
Giants vs Diamondbacks latest injuries
Giants vs Diamondbacks weather
Odds are correct at the time of publishing and are subject to change.
Not intended for use in MA.
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