Get first element's attribute in Powershell

I am writing an automated site backup powershell script.

I have the following xml in an [xml] casted variable obtained from appcmd.exe:

<application path="/" applicationPool="komplus.ua-PROD">     
  <virtualDirectoryDefaults />  
  <virtualDirectory path="/" physicalPath="C:\WEB\PROD\komplus.ua" />       
</application>
<application path="/kb" applicationPool="komplus.ua-PROD" enabledProtocols="http, https">
  <virtualDirectoryDefaults /> 
  <virtualDirectory path="/" physicalPath="C:\WEB\PROD\komplus.ua\kb" />
</application>

The xml is in the variable $xmlInput.

I need to get the value of the physicalPath attribute of VirtualDirectory element in first application element.

I've tried several options, including custom Get-XmlElement functions, but can't seem to get to the value.

Currently I have:

 $selectResult = $xmlInput.application.virtualDirectory | Select physicalPath

But the $selectResult is null.

Please assist in which parsing is correct to get the value I need.