Nginx – Rewrite url with fastcgi in nginx

I have a working php fastcgi config in nginx. Now I have few requests to handle such as /X.php by /X, /Y.php by /Y
Sounds simple so I wrote the following for testing:

rewrite ^/X.php$ /api/v1/stat last;

it was caught by php application's 404 handler. here is the nginx error log with rewrite_log on

[notice] 15289#0: *759 "^/X.php$" matches "/X.php", client: 10.0.0.12, server: example.com, request: "GET /X.php HTTP/1.1", host: "example.com"
[notice] 15289#0: *759 rewritten data: "/api/v1/stat", args: "", client: 10.0.0.12, server: example.com, request: "GET /X.php HTTP/1.1", host: "example.com"
[notice] 15289#0: *759 "^/X.php$" does not match "/index.php", client: 10.0.0.12, server: example.com, request: "GET /X.php HTTP/1.1", host: "example.com"

If I visit /api/v1/stat directly, it works:

[notice] 15125#0: *708 "^/X.php$" does not match "/api/v1/stat", client: 223.104.3.248, server: example.com, request: "GET /api/v1/stat HTTP/1.1", host: "example.com"
[notice] 15125#0: *708 "^/X.php$" does not match "/index.php", client: 223.104.3.248, server: example.com, request: "GET /api/v1/stat HTTP/1.1", host: "example.com"

Here is my related nginx config:

rewrite ^/X.php$    /api/v1/stat last;

location / {
    try_files $uri $uri/ /index.php;
}

location ~ .*\.php$ {
    try_files $uri =404;
    include        fastcgi_params;
    fastcgi_pass   php;
    fastcgi_index  index.php;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
}

upstream php {
    server unix:/var/run/php-fpm.sock;
}

Please help me come up a solution. thanks.

NOTE

A little background that may help you understand my problem.

It is probably obvious that the following should work and it does:

rewrite ^/X.php$ /api/v1/stat permanent;

However, I am dealing with some kind of hardware that doesn't understand 301 redirect, so I am trying to do with internal redirect without revealing the redirect.

UPDATE 1

The solution I came up is a half only. I got /X.php redirect to /api/v1/stat fine. However, no parameters can be passed after the redirect. I think rewrite will pass along the $args but it doesnt work. I am at a loss now..

UPDATE 2

Problem solved. though I am still not sure why $args is not passing along.