The Boston Celtics got a 102-88 win over the Miami Heat on Monday night to extend their lead to 3-1, but they lost a key piece as Kristaps Porzingis went down with an injury. The team announced that he is dealing with a right soleus strain and will miss Game 5 of their first-round playoff series against the Heat on Wednesday, per NBA insiders Adrian Wojnarowski and Tim Bontemps.Kristaps Porzingis' latest injury update as per Chris Haynes is that he will likely miss the entire Eastern Conference Semi-Finals. Porzingis, who is dealing with a right calf strain, is sidelined for the upcoming series and beyond. However, there's optimism that he might be able to make a comeback if the Celtics progress to the Eastern Conference Finals.As the Celtics' starting center this season, he averaged 20.1 points, 7.2 rebounds, and 1.9 blocks in 57 games played. He has been less productive in the playoffs, only averaging 12.3 points and 5.0 rebounds through the first four games, but that does not mean he's been ineffective.He is a plus defender for the Celtics, and in their series, he has a defensive rating of 99 and is averaging 4.2 +/-.Also read: “Do all the dirty things they can”: Celtics’ Kristaps Porzingis acknowledges team is ready for a rough Miami HeatHow have the Boston Celtics performed without Kristaps PorzingisThe Boston Celtics were the best team in the league throughout the 2023-24 regular season, thanks in large part to their stacked lineup. Despite Kristaps Porzingis missing 25 of their 82 games this season, they still came out on top of the NBA with a 64-18 record.Out of those 25 games that Porzingis missed, the Celtics were defeated just four times. They lost by 10 against the Indiana Pacers on Dec. 4, with Al Horford replacing him in the lineup. Then on Dec. 19, they suffered another loss against the Golden State Warriors, this time by six. Horford was once again inserted into the lineup to replace the injured starter.Their biggest loss without Porzingis in the lineup was against the LA Clippers on Jan. 27, when they were beaten by a 19-point margin in a 115-96 defeat. Finally, they lost to the Milwaukee Bucks by 13 on April 9.While these games were in the regular season, it's a good sign that the Celtics only lost four games with Kristaps Porzingis out. It showcases their depth, which will definitely come in handy for the remainder of the playoffs.Who will replace Kristaps Porzingis in the starting lineup?Just like in the regular season, expect Al Horford to fill in for Kristaps Porzingis in the starting lineup. Horford, a 37-year-old vet, has stepped up whenever his team has needed him.His experience and his IQ will come in handy for the Celtics while Porzingis is out with his soleus injury.