Add a second class to last post in loop

Hi,

I would like to add “last” to <article class=”post”> to be this <article class”post last”>

Here is what I have so far:

<?php $most_popular_query = new WP_Query( array( 'category_name' => 'player-news', 'posts_per_page' => 1 ) );
while ( $most_popular_query->have_posts() ) : $most_popular_query->the_post(); ?>

<article class="post">

<div class="thumb"><a href="<?php the_permalink() ?>"><?php the_post_thumbnail( 'frontpage-most-popular-thumb' ); ?></a></div>

<div class="cat"><?php the_category(', ') ?></div>

<h3><a href="<?php the_permalink() ?>" title="<?php the_title_attribute(); ?>"><?php echo(get_the_title()); ?></a></h3>

<div class="activity">
<span class="views">12</span><span class="comment"><a href="#"><?php $comments_count = wp_count_comments(post_id);echo $comments_count->total_comments;?></a></span>
</div>
</article><!--  /.post -->

<?php endwhile; 

// Reset Query
wp_reset_query();
?>

<article class="post last">
<div class="thumb">
<a href="#"><img src="<?php echo esc_url( get_template_directory_uri() ); ?>/images/thumbs/7.jpg" alt="img"></a>
</div>
<div class="cat">
<a href="">Social media</a>
</div>
<h3><a href="#">I'm not claiming the multiplier is precisely 36, but it is certainly more than 10...</a></h3>
<div class="activity">
<span class="views">12</span><span class="comment"><a href="#">0</a></span>
</div>
</article><!--  /.post -->

I want to know how I can add a function inside my while loop to do this on the last post. Also, to make it easier, I don’t need the function to count current posts and determine which one is the last one. Essentially, there will be two posts in this loop, so I need to apply “last” to the class of the second post.

Thank you!