Both :nth-child and :last-child

Both :nth-child and :last-child

Code:
<table>
<tr>
<td></td>
<td></td>
<td></td>
<td colspan="2"></td> <==== Only this
</tr>
<tr>
<td></td>
<td></td>
<td colspan="3"></td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
</table>
I want to select only the fourth "td" but only if it's the last. Can I do
this?
tr td:last-child:nth-child(4) { /* Some Style */ }