SAN FRANCISCO -- Zack Wheeler took another tangible step forward Sunday on his road back from a right shoulder impingement, throwing a bullpen session at Oracle Park. While Wheeler is likely to return on the Mets' upcoming homestand, the team is not currently planning to start him before Friday against the Pirates. That will give Wheeler, a prime trade candidate, only one more outing before the July 31 deadline.

A final decision on Wheeler's activation will not come until Monday, after the Mets see how his arm responds to Sunday's workload. Wheeler was terse when asked about the session, answering every question by saying simply that it went "good," but manager Mickey Callaway affirmed that all went well.

"If he feels good [Monday], we've got to figure out when to plug him in," Callaway said.

Although Wheeler is eligible to come off the injured list Monday, the Mets may first ask him to throw a simulated game against live hitters. The team has tentatively slotted Jason Vargas, Noah Syndergaard and Jacob deGrom to pitch in their regular rotation spots Tuesday through Thursday, eliminating any chance that Wheeler could start twice before the Trade Deadline.

In 19 starts, Wheeler is 6-6 with a 4.69 ERA. He is considered one of the top starters available at the July 31 deadline.

Baseball royalty

Mets quality-control coach Luis Rojas had a pregame reunion Sunday with his father, 84-year-old Felipe Alou. Alou was a three-time All-Star and the 1994 National League Manager of the Year, as well as the father of both Rojas and former Mets outfielder Moises Alou.

Blood drive

The Mets will hold their semi-annual blood drive Monday from 11 a.m. to 6 p.m. ET at Citi Field. Fans who donate will receive two tickets to a select Mets home game at Citi Field.