NEW YORK -- How much lower can the New York Mets sink?

With three losses this week to the San Diego Padres, the answer will finally be to the very bottom of the National League.

The Mets will begin a three-game series against the only team cushioning their fall to the bottom of the Senior Circuit on Monday, when the NL-worst Padres visit Citi Field.

Mets ace right-hander Jacob deGrom (5-4, 1.68 ERA) is scheduled to oppose Padres rookie left-hander Eric Lauer (5-6, 4.87 ERA).

Both teams are coming off a rain-impacted first series following the All-Star Game. The visiting Padres split a doubleheader with the Philadelphia Phillies on Sunday, when San Diego won the opener, 10-2, before falling, 5-0, in the nightcap. The twinbill was caused by a rainout on Saturday.

DeGrom's first start of the second half was pushed back when the finale of the Mets' three-game series against the New York Yankees was rained out Sunday night. The Mets fell to the Yankees, 7-6, on Saturday and are two games ahead of the Padres in the race to avoid the worst record in the NL.

The rainout Sunday capped a weird-even-by-their-standards weekend for the Mets (40-56), who missed out on a chance to climb out of sole possession of last place in the NL East and into a virtual tie for fourth place with the Miami Marlins.

The weekend began with Yoenis Cespedes coming off the disabled list, where he spent the previous nine weeks due to mysterious lower leg injuries and hitting a homer in the Mets' 7-5 win. But afterward, Cespedes told reporters he's been battling a calcification issue in both his heels, ailments that could require surgery that would sideline him well into next season.

Cespedes didn't play Saturday, when the Mets traded closer Jeurys Familia to the Oakland Athletics in exchange for a pair of low-level prospects and international slot money. On Sunday, John Ricco, one of the three executives filling the general manager's role following the health-related leave of absence for Sandy Alderson, said there was no disconnect between the team and Cespedes but that they didn't know if he'd go on the disabled list or play this week.

If the Mets don't put Cespedes on the DL and rule him out of Monday's game, they would be playing with at least one man short for the third straight game. They held Familia out Friday and Saturday before trading him and did not use Cespedes even in a pinch-hitting role with the bases loaded in a one-run game in the ninth inning.

Oh, and Ricco ended a 31-minute press conference by announcing right-hander Noah Syndergaard was placed on the 10-day disabled list due to hand, foot and mouth disease, a painful ailment most often associated with preschool children. The Mets think Syndergaard may have caught the illness while appearing at a day camp during the All-Star Break.

"Hand, foot and mouth, are you serious? Mets manager Mickey Callaway said prior to Sunday's postponement. "I guess it's very uncommon in adults, period. It's kind of odd. Maybe the first DL stint in Major League Baseball with hand, foot and mouth, I don't know. A record or something."

The Padres (41-61), meanwhile, are simply enduring another routine season in their ongoing rebuild. San Diego, which is on pace for its eight straight sub-.500 campaign, dealt closer Brad Hand and rookie set-up man Adam Cimber to the Cleveland Indians last Thursday in exchange for top catching prospect Francisco Mejia.

"Where we're at in the standings, the second part of the year will be (about) looking at improvement from our club, looking at improvement from individuals and giving opportunities to guys that have some talent," Padres general manager A.J. Preller told reporters Thursday. "We'll see if we can find the next Brad Hand or the next Adam Cimber."

DeGrom, who allowed a Mike Trout home run during an inning of work in the All-Star Game last Tuesday, didn't factor into the decision in his most recent start for the Mets on July 11, when he allowed five hits over eight scoreless innings in New York's 3-0, 10-inning win over the Phillies. It was the seventh time this season deGrom, who leads the majors in ERA, failed to earn the win despite allowing one run or fewer over at least seven innings.

Lauer took the loss in his most recent start July 15, when he allowed five runs over two innings as the Padres fell to the Chicago Cubs, 7-4. It was the shortest start for Lauer in 18 big league appearances.

DeGrom is 3-1 with a 1.53 ERA in five career starts against the Padres. Lauer has never faced the Mets.