Francisco Alvarez's much-awaited return to the New York Mets lineup will have to wait. That's because the catcher has had a setback in rehab with the Triple-A affiliate Syracuse Mets after being hit on his left pinky finger, fracturing it.Mets manager Carlos Mendoza opened up about Alvarez's injury ahead of the series against the Miami Marlins on Thursday. He termed the injury to be a bit of a setback to the original plan of bringing Alvarez back into the lineup."This should be relatively short," Mendoza said. "But, again, it's a little bit of a setback compared to what the original plan was. But when you're talking about you get the news, 'Oh, he's got a fracture,' you're thinking about the worst-case scenario, but apparently, that's not the case here. So we just got to wait and see."The 23-year-old was on the sidelines since Aug. 17 when he sprained his right thumb's ACL while trying to reach second base. It's the same finger where he tore a ligament last season, which put him on the Injured List for two months. With the left pinky fracture, this is the fourth hand injury for Francisco Alvarez, having missed the first month of the current regular season after fracturing his left hamate bone.The Venezuelan has kept his spirts up, though, writing a heartfelt message on Instagram.Francisco Alvarez's Instagram story (Source: Instagram @franciscoalvarez.13)"Oh my God, thank you for everything you give us, thank you for each day, for being healthy, thank you for teaching me to be more patient, more and more, it's your time, whenever you want, I will keep trying again and again," the translated version of his caption read.Alvarez will require a surgery to fix his sprained UCL on the right hand. After the surgery, he will need an eight-week rehab period, meaning if has to get some action in the current season, he has to play through pain and delay his surgery for the postseason. Now with the left pinky fracture, his return date has been to put into question.The Mets don't want an uncomfortable position for Francisco AlvarezMets coach Carlos Mendoza said that while they believe in Francisco Alvarez's work ethic and pain tolerance, they aren't willing to push the limits."We're not going to put him in a position where he's very uncomfortable," Mendoza said. "As tough as he is, he's human. So, I think we got to get him to a point where it's manageable because now we're talking about the receiving hand, too. But, again, it's a small fracture, and we just got to wait. But it comes down to making sure we're not putting the player in a position where he's in danger."Francisco Alvarez was batting at .323 with a 1.054 OPS in the 21 games before the UCL sprain injury. This was a rejuvenated version of him that sprang to life after a brief spell in the Triple-A because of lack of form in the first half.